diff --git a/bin/lessc b/bin/lessc
index 7360ff07e..5387fb950 100755
--- a/bin/lessc
+++ b/bin/lessc
@@ -4,6 +4,7 @@ var path = require('path'),
     fs = require('../lib/less-node/fs'),
     os = require('os'),
     utils = require('../lib/less/utils'),
+    MATH = require('../lib/less/math-constants'),
     errno,
     mkdirp;
 
@@ -481,8 +482,17 @@ function processPluginQueue() {
                 break;
             case 'sm':
             case 'strict-math':
+                console.warning('--strict-math is deprecated. Use --math=strict');
                 if (checkArgFunc(arg, match[2])) {
-                    options.strictMath = checkBooleanArg(match[2]);
+                    if (checkBooleanArg(match[2])) {
+                        options.math = MATH.STRICT_LEGACY;
+                    }
+                }
+                break;
+            case 'm':
+            case 'math':
+                if (checkArgFunc(arg, match[2])) {
+                    options.math = match[2];
                 }
                 break;
             case 'su':
diff --git a/lib/less-browser/add-default-options.js b/lib/less-browser/add-default-options.js
index 5155afbce..051a68dd8 100644
--- a/lib/less-browser/add-default-options.js
+++ b/lib/less-browser/add-default-options.js
@@ -42,8 +42,4 @@ module.exports = function(window, options) {
     if (options.onReady === undefined) {
         options.onReady = true;
     }
-
-    // TODO: deprecate and remove 'inlineJavaScript' thing - where it came from at all?
-    options.javascriptEnabled = (options.javascriptEnabled || options.inlineJavaScript) ? true : false;
-
 };
diff --git a/lib/less-node/lessc-helper.js b/lib/less-node/lessc-helper.js
index 8b40f4fdf..fced0a56c 100644
--- a/lib/less-node/lessc-helper.js
+++ b/lib/less-node/lessc-helper.js
@@ -48,9 +48,13 @@ var lessc_helper = {
         console.log('  -rp, --rootpath=URL          Sets rootpath for url rewriting in relative imports and urls');
         console.log('                               Works with or without the relative-urls option.');
         console.log('  -ru, --relative-urls         Re-writes relative urls to the base less file.');
-        console.log('  -sm=on|off                   Turns on or off strict math, where in strict mode, math.');
-        console.log('  --strict-math=on|off         Requires brackets. This option may default to on and then');
-        console.log('                               be removed in the future.');
+        console.log('');
+        console.log('  -m=, --math=');
+        console.log('     always                    Less will eagerly perform math operations always.');
+        console.log('     parens-division           Math performed except for division (/) operator');
+        console.log('     parens | strict           Math only performed inside parentheses');
+        console.log('     strict-legacy             Parens required in very strict terms (legacy --strict-math)');
+        console.log('');
         console.log('  -su=on|off                   Allows mixed units, e.g. 1px+1em or 1px*1px which have units');
         console.log('  --strict-units=on|off        that cannot be represented.');
         console.log('  --global-var=\'VAR=VALUE\'     Defines a variable that can be referenced by the file.');
@@ -64,6 +68,9 @@ var lessc_helper = {
         console.log('                               or --clean-css="advanced"');
         console.log('');
         console.log('-------------------------- Deprecated ----------------');
+        console.log('  -sm=on|off               Legacy parens-only math. Use --math');
+        console.log('  --strict-math=on|off     ');
+        console.log('');
         console.log('  --line-numbers=TYPE      Outputs filename and line numbers.');
         console.log('                           TYPE can be either \'comments\', which will output');
         console.log('                           the debug info within comments, \'mediaquery\'');
diff --git a/lib/less/contexts.js b/lib/less/contexts.js
index a2f712110..69b84cacd 100644
--- a/lib/less/contexts.js
+++ b/lib/less/contexts.js
@@ -1,5 +1,6 @@
 var contexts = {};
 module.exports = contexts;
+var MATH = require('./math-constants');
 
 var copyFromOriginal = function copyFromOriginal(original, destination, propertiesToCopy) {
     if (!original) { return; }
@@ -43,7 +44,7 @@ var evalCopyProperties = [
     'paths',             // additional include paths
     'compress',          // whether to compress
     'ieCompat',          // whether to enforce IE compatibility (IE8 data-uri)
-    'strictMath',        // whether math has to be within parenthesis
+    'math',              // whether math has to be within parenthesis
     'strictUnits',       // whether units need to evaluate correctly
     'sourceMap',         // whether to output a source map
     'importMultiple',    // whether we are currently importing multiple copies
@@ -90,11 +91,17 @@ contexts.Eval.prototype.outOfParenthesis = function () {
 
 contexts.Eval.prototype.inCalc = false;
 contexts.Eval.prototype.mathOn = true;
-contexts.Eval.prototype.isMathOn = function () {
+contexts.Eval.prototype.isMathOn = function (op) {
     if (!this.mathOn) {
         return false;
     }
-    return this.strictMath ? (this.parensStack && this.parensStack.length) : true;
+    if (op === '/' && this.math !== MATH.ALWAYS && (!this.parensStack || !this.parensStack.length)) {
+        return false;
+    }
+    if (this.math > MATH.PARENS_DIVISION) {
+        return this.parensStack && this.parensStack.length;
+    }
+    return true;
 };
 
 contexts.Eval.prototype.isPathRelative = function (path) {
diff --git a/lib/less/default-options.js b/lib/less/default-options.js
index 09c0b3cfe..2ff9d2dc2 100644
--- a/lib/less/default-options.js
+++ b/lib/less/default-options.js
@@ -1,10 +1,13 @@
 // Export a new default each time
 module.exports = function() {
     return {
+        /* Inline Javascript - @plugin still allowed */
+        javascriptEnabled: false,
+
         /* Outputs a makefile import dependency list to stdout. */
         depends: false,
 
-        /* Compress using less built-in compression. 
+        /* (DEPRECATED) Compress using less built-in compression. 
          * This does an okay job but does not utilise all the tricks of 
          * dedicated css compression. */
         compress: false,
@@ -44,8 +47,13 @@ module.exports = function() {
         /* Compatibility with IE8. Used for limiting data-uri length */
         ieCompat: false,  // true until 3.0
 
-        /* Without this option on, Less will try and process all math in your css */
-        strictMath: false,
+        /* How to process math 
+         *   0 always           - eagerly try to solve all operations
+         *   1 parens-division  - require parens for division "/"
+         *   2 parens | strict  - require parens for all operations
+         *   3 strict-legacy    - legacy strict behavior (super-strict)
+         */
+        math: 0,
 
         /* Without this option, less attempts to guess at the output unit when it does maths. */
         strictUnits: false,
diff --git a/lib/less/math-constants.js b/lib/less/math-constants.js
new file mode 100644
index 000000000..6b8af9299
--- /dev/null
+++ b/lib/less/math-constants.js
@@ -0,0 +1,6 @@
+module.exports = {
+    ALWAYS: 0,
+    PARENS_DIVISION: 1,
+    PARENS: 2,
+    STRICT_LEGACY: 3
+};
\ No newline at end of file
diff --git a/lib/less/parse.js b/lib/less/parse.js
index d1c4fad5d..cc254ba30 100644
--- a/lib/less/parse.js
+++ b/lib/less/parse.js
@@ -10,10 +10,10 @@ module.exports = function(environment, ParseTree, ImportManager) {
 
         if (typeof options === 'function') {
             callback = options;
-            options = utils.defaults(this.options, {});
+            options = utils.copyOptions(this.options, {});
         }
         else {
-            options = utils.defaults(this.options, options || {});
+            options = utils.copyOptions(this.options, options || {});
         }
 
         if (!callback) {
diff --git a/lib/less/parser/parser.js b/lib/less/parser/parser.js
index edb1db0ca..71abd8960 100644
--- a/lib/less/parser/parser.js
+++ b/lib/less/parser/parser.js
@@ -1947,7 +1947,7 @@ var Parser = function Parser(context, imports, fileInfo) {
 
                         parserInput.save();
 
-                        op = parserInput.$char('/') || parserInput.$char('*');
+                        op = parserInput.$char('/') || parserInput.$char('*') || parserInput.$str('./');
 
                         if (!op) { parserInput.forget(); break; }
 
diff --git a/lib/less/render.js b/lib/less/render.js
index 1743f352e..8ea6f9eaa 100644
--- a/lib/less/render.js
+++ b/lib/less/render.js
@@ -5,10 +5,10 @@ module.exports = function(environment, ParseTree, ImportManager) {
     var render = function (input, options, callback) {
         if (typeof options === 'function') {
             callback = options;
-            options = utils.defaults(this.options, {});
+            options = utils.copyOptions(this.options, {});
         }
         else {
-            options = utils.defaults(this.options, options || {});
+            options = utils.copyOptions(this.options, options || {});
         }
 
         if (!callback) {
diff --git a/lib/less/tree/declaration.js b/lib/less/tree/declaration.js
index 203c67c3e..c0b327d0a 100644
--- a/lib/less/tree/declaration.js
+++ b/lib/less/tree/declaration.js
@@ -1,7 +1,8 @@
 var Node = require('./node'),
     Value = require('./value'),
     Keyword = require('./keyword'),
-    Anonymous = require('./anonymous');
+    Anonymous = require('./anonymous'),
+    MATH = require('../math-constants');
 
 var Declaration = function (name, value, important, merge, index, currentFileInfo, inline, variable) {
     this.name = name;
@@ -41,7 +42,7 @@ Declaration.prototype.genCSS = function (context, output) {
     output.add(this.important + ((this.inline || (context.lastRule && context.compress)) ? '' : ';'), this._fileInfo, this._index);
 };
 Declaration.prototype.eval = function (context) {
-    var strictMathBypass = false, name = this.name, evaldValue, variable = this.variable;
+    var mathBypass = false, prevMath, name = this.name, evaldValue, variable = this.variable;
     if (typeof name !== 'string') {
         // expand 'primitive' name directly to get
         // things faster (~10% for benchmark.less):
@@ -49,9 +50,12 @@ Declaration.prototype.eval = function (context) {
                 name[0].value : evalName(context, name);
         variable = false; // never treat expanded interpolation as new variable name
     }
-    if (name === 'font' && !context.strictMath) {
-        strictMathBypass = true;
-        context.strictMath = true;
+
+    // @todo remove when parens-division is default
+    if (name === 'font' && context.math === MATH.ALWAYS) {
+        mathBypass = true;
+        prevMath = context.math;
+        context.math = MATH.PARENS_DIVISION;
     }
     try {
         context.importantScope.push({});
@@ -82,8 +86,8 @@ Declaration.prototype.eval = function (context) {
         throw e;
     }
     finally {
-        if (strictMathBypass) {
-            context.strictMath = false;
+        if (mathBypass) {
+            context.math = prevMath;
         }
     }
 };
diff --git a/lib/less/tree/expression.js b/lib/less/tree/expression.js
index 92cad86cf..7e0ff1a04 100644
--- a/lib/less/tree/expression.js
+++ b/lib/less/tree/expression.js
@@ -1,6 +1,8 @@
 var Node = require('./node'),
     Paren = require('./paren'),
-    Comment = require('./comment');
+    Comment = require('./comment'),
+    Dimension = require('./dimension'),
+    MATH = require('../math-constants');
 
 var Expression = function (value, noSpacing) {
     this.value = value;
@@ -17,7 +19,8 @@ Expression.prototype.accept = function (visitor) {
 Expression.prototype.eval = function (context) {
     var returnValue,
         mathOn = context.isMathOn(),
-        inParenthesis = this.parens && !this.parensInOp,
+        inParenthesis = this.parens && 
+            (context.math !== MATH.STRICT_LEGACY || !this.parensInOp),
         doubleParen = false;
     if (inParenthesis) {
         context.inParenthesis();
@@ -40,7 +43,8 @@ Expression.prototype.eval = function (context) {
     if (inParenthesis) {
         context.outOfParenthesis();
     }
-    if (this.parens && this.parensInOp && !mathOn && !doubleParen) {
+    if (this.parens && this.parensInOp && !mathOn && !doubleParen 
+        && (!(returnValue instanceof Dimension))) {
         returnValue = new Paren(returnValue);
     }
     return returnValue;
diff --git a/lib/less/tree/operation.js b/lib/less/tree/operation.js
index 910c8b064..08ac152b3 100644
--- a/lib/less/tree/operation.js
+++ b/lib/less/tree/operation.js
@@ -1,6 +1,7 @@
 var Node = require('./node'),
     Color = require('./color'),
-    Dimension = require('./dimension');
+    Dimension = require('./dimension'),
+    MATH = require('../math-constants');
 
 var Operation = function (op, operands, isSpaced) {
     this.op = op.trim();
@@ -14,9 +15,11 @@ Operation.prototype.accept = function (visitor) {
 };
 Operation.prototype.eval = function (context) {
     var a = this.operands[0].eval(context),
-        b = this.operands[1].eval(context);
+        b = this.operands[1].eval(context),
+        op;
 
-    if (context.isMathOn()) {
+    if (context.isMathOn(this.op)) {
+        op = this.op === './' ? '/' : this.op;
         if (a instanceof Dimension && b instanceof Color) {
             a = a.toColor();
         }
@@ -24,11 +27,14 @@ Operation.prototype.eval = function (context) {
             b = b.toColor();
         }
         if (!a.operate) {
+            if (a instanceof Operation && a.op === '/' && context.math === MATH.PARENS_DIVISION) {
+                return new Operation(this.op, [a, b], this.isSpaced);
+            }
             throw { type: 'Operation',
                 message: 'Operation on an invalid type' };
         }
 
-        return a.operate(context, this.op, b);
+        return a.operate(context, op, b);
     } else {
         return new Operation(this.op, [a, b], this.isSpaced);
     }
diff --git a/lib/less/utils.js b/lib/less/utils.js
index 1c830e7c8..ff260d632 100644
--- a/lib/less/utils.js
+++ b/lib/less/utils.js
@@ -1,4 +1,6 @@
 /* jshint proto: true */
+var MATH = require('./math-constants');
+
 var utils = {
     getLocation: function(index, inputStream) {
         var n = index + 1,
@@ -36,6 +38,29 @@ var utils = {
         }
         return cloned;
     },
+    copyOptions: function(obj1, obj2) {
+        var opts = utils.defaults(obj1, obj2);
+        if (opts.strictMath) {
+            opts.math = MATH.STRICT_LEGACY;
+        }
+        if (opts.hasOwnProperty('math') && typeof opts.math === 'string') {
+            switch (opts.math.toLowerCase()) {
+                case 'always':
+                    opts.math = MATH.ALWAYS;
+                    break;
+                case 'parens-division':
+                    opts.math = MATH.PARENS_DIVISION;
+                    break;
+                case 'strict':
+                case 'parens':
+                    opts.math = MATH.PARENS;
+                    break;
+                case 'strict-legacy':
+                    opts.math = MATH.STRICT_LEGACY;
+            }
+        }
+        return opts;
+    },
     defaults: function(obj1, obj2) {
         if (!obj2._defaults || obj2._defaults !== obj1) {
             for (var prop in obj1) {
diff --git a/package-lock.json b/package-lock.json
index 0bd5290dc..5c36b9d51 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "less",
-  "version": "3.5.2",
+  "version": "3.5.3",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
@@ -3276,9 +3276,9 @@
       }
     },
     "grunt-contrib-jasmine": {
-      "version": "1.1.0",
-      "resolved": "https://registry.npmjs.org/grunt-contrib-jasmine/-/grunt-contrib-jasmine-1.1.0.tgz",
-      "integrity": "sha1-9oL3dX2il3Wf4+G0xl1GcMw66kk=",
+      "version": "1.2.0",
+      "resolved": "https://registry.npmjs.org/grunt-contrib-jasmine/-/grunt-contrib-jasmine-1.2.0.tgz",
+      "integrity": "sha512-1mTRFLsHupOzP0JOSkKIROudMyFVOiBy96dX3/rHCn71z3kkpm6Ch5e71qNozeRfZgAPjf/7mDyQ/uDaS+D8IA==",
       "dev": true,
       "requires": {
         "chalk": "1.1.3",
@@ -3408,7 +3408,7 @@
       "dev": true,
       "requires": {
         "eventemitter2": "0.4.14",
-        "phantomjs-prebuilt": "2.1.15",
+        "phantomjs-prebuilt": "2.1.16",
         "rimraf": "2.6.2",
         "semver": "5.4.1",
         "temporary": "0.0.8"
@@ -4831,9 +4831,9 @@
       "dev": true
     },
     "phantomjs-prebuilt": {
-      "version": "2.1.15",
-      "resolved": "https://registry.npmjs.org/phantomjs-prebuilt/-/phantomjs-prebuilt-2.1.15.tgz",
-      "integrity": "sha1-IPhugtM0nFBZF1J3RbekEeCLOQM=",
+      "version": "2.1.16",
+      "resolved": "https://registry.npmjs.org/phantomjs-prebuilt/-/phantomjs-prebuilt-2.1.16.tgz",
+      "integrity": "sha1-79ISpKOWbTZHaE6ouniFSb4q7+8=",
       "dev": true,
       "requires": {
         "es6-promise": "4.0.5",
@@ -4842,146 +4842,15 @@
         "hasha": "2.2.0",
         "kew": "0.7.0",
         "progress": "1.1.8",
-        "request": "2.81.0",
+        "request": "2.83.0",
         "request-progress": "2.0.1",
-        "which": "1.2.14"
+        "which": "1.3.1"
       },
       "dependencies": {
-        "assert-plus": {
-          "version": "0.2.0",
-          "resolved": "https://registry.npmjs.org/assert-plus/-/assert-plus-0.2.0.tgz",
-          "integrity": "sha1-104bh+ev/A24qttwIfP+SBAasjQ=",
-          "dev": true
-        },
-        "aws-sign2": {
-          "version": "0.6.0",
-          "resolved": "https://registry.npmjs.org/aws-sign2/-/aws-sign2-0.6.0.tgz",
-          "integrity": "sha1-FDQt0428yU0OW4fXY81jYSwOeU8=",
-          "dev": true
-        },
-        "boom": {
-          "version": "2.10.1",
-          "resolved": "https://registry.npmjs.org/boom/-/boom-2.10.1.tgz",
-          "integrity": "sha1-OciRjO/1eZ+D+UkqhI9iWt0Mdm8=",
-          "dev": true,
-          "requires": {
-            "hoek": "2.16.3"
-          }
-        },
-        "cryptiles": {
-          "version": "2.0.5",
-          "resolved": "https://registry.npmjs.org/cryptiles/-/cryptiles-2.0.5.tgz",
-          "integrity": "sha1-O9/s3GCBR8HGcgL6KR59ylnqo7g=",
-          "dev": true,
-          "requires": {
-            "boom": "2.10.1"
-          }
-        },
-        "form-data": {
-          "version": "2.1.4",
-          "resolved": "https://registry.npmjs.org/form-data/-/form-data-2.1.4.tgz",
-          "integrity": "sha1-M8GDrPGTJ27KqYFDpp6Uv+4XUNE=",
-          "dev": true,
-          "requires": {
-            "asynckit": "0.4.0",
-            "combined-stream": "1.0.6",
-            "mime-types": "2.1.17"
-          }
-        },
-        "har-schema": {
-          "version": "1.0.5",
-          "resolved": "https://registry.npmjs.org/har-schema/-/har-schema-1.0.5.tgz",
-          "integrity": "sha1-0mMTX0MwfALGAq/I/pWXDAFRNp4=",
-          "dev": true
-        },
-        "har-validator": {
-          "version": "4.2.1",
-          "resolved": "https://registry.npmjs.org/har-validator/-/har-validator-4.2.1.tgz",
-          "integrity": "sha1-M0gdDxu/9gDdID11gSpqX7oALio=",
-          "dev": true,
-          "requires": {
-            "ajv": "4.11.8",
-            "har-schema": "1.0.5"
-          }
-        },
-        "hawk": {
-          "version": "3.1.3",
-          "resolved": "https://registry.npmjs.org/hawk/-/hawk-3.1.3.tgz",
-          "integrity": "sha1-B4REvXwWQLD+VA0sm3PVlnjo4cQ=",
-          "dev": true,
-          "requires": {
-            "boom": "2.10.1",
-            "cryptiles": "2.0.5",
-            "hoek": "2.16.3",
-            "sntp": "1.0.9"
-          }
-        },
-        "hoek": {
-          "version": "2.16.3",
-          "resolved": "https://registry.npmjs.org/hoek/-/hoek-2.16.3.tgz",
-          "integrity": "sha1-ILt0A9POo5jpHcRxCo/xuCdKJe0=",
-          "dev": true
-        },
-        "http-signature": {
-          "version": "1.1.1",
-          "resolved": "https://registry.npmjs.org/http-signature/-/http-signature-1.1.1.tgz",
-          "integrity": "sha1-33LiZwZs0Kxn+3at+OE0qPvPkb8=",
-          "dev": true,
-          "requires": {
-            "assert-plus": "0.2.0",
-            "jsprim": "1.4.1",
-            "sshpk": "1.13.1"
-          }
-        },
-        "qs": {
-          "version": "6.4.0",
-          "resolved": "https://registry.npmjs.org/qs/-/qs-6.4.0.tgz",
-          "integrity": "sha1-E+JtKK1rD/qpExLNO/cI7TUecjM=",
-          "dev": true
-        },
-        "request": {
-          "version": "2.81.0",
-          "resolved": "https://registry.npmjs.org/request/-/request-2.81.0.tgz",
-          "integrity": "sha1-xpKJRqDgbF+Nb4qTM0af/aRimKA=",
-          "dev": true,
-          "requires": {
-            "aws-sign2": "0.6.0",
-            "aws4": "1.6.0",
-            "caseless": "0.12.0",
-            "combined-stream": "1.0.6",
-            "extend": "3.0.1",
-            "forever-agent": "0.6.1",
-            "form-data": "2.1.4",
-            "har-validator": "4.2.1",
-            "hawk": "3.1.3",
-            "http-signature": "1.1.1",
-            "is-typedarray": "1.0.0",
-            "isstream": "0.1.2",
-            "json-stringify-safe": "5.0.1",
-            "mime-types": "2.1.17",
-            "oauth-sign": "0.8.2",
-            "performance-now": "0.2.0",
-            "qs": "6.4.0",
-            "safe-buffer": "5.1.1",
-            "stringstream": "0.0.5",
-            "tough-cookie": "2.3.3",
-            "tunnel-agent": "0.6.0",
-            "uuid": "3.2.1"
-          }
-        },
-        "sntp": {
-          "version": "1.0.9",
-          "resolved": "https://registry.npmjs.org/sntp/-/sntp-1.0.9.tgz",
-          "integrity": "sha1-ZUEYTMkK7qbG57NeJlkIJEPGYZg=",
-          "dev": true,
-          "requires": {
-            "hoek": "2.16.3"
-          }
-        },
         "which": {
-          "version": "1.2.14",
-          "resolved": "https://registry.npmjs.org/which/-/which-1.2.14.tgz",
-          "integrity": "sha1-mofEN48D6CfOyvGs31bHNsAcFOU=",
+          "version": "1.3.1",
+          "resolved": "https://registry.npmjs.org/which/-/which-1.3.1.tgz",
+          "integrity": "sha512-HxJdYWq1MTIQbJ3nw0cqssHoTNU267KlrDuGZ1WYlxDStUtKUhOaJmh112/TZmHxxUfuJqPXSOm7tDyas0OSIQ==",
           "dev": true,
           "requires": {
             "isexe": "2.0.0"
diff --git a/test/browser/runner-browser-options.js b/test/browser/runner-browser-options.js
index be8e3e3e1..780de3861 100644
--- a/test/browser/runner-browser-options.js
+++ b/test/browser/runner-browser-options.js
@@ -2,7 +2,7 @@ var less = {
     logLevel: 4, 
     errorReporting: 'console', 
     javascriptEnabled: true,
-    strictMath: false
+    math: 'always'
 };
 
 // There originally run inside describe method. However, since they have not
diff --git a/test/browser/runner-errors-options.js b/test/browser/runner-errors-options.js
index 97b211d93..852ea5f71 100644
--- a/test/browser/runner-errors-options.js
+++ b/test/browser/runner-errors-options.js
@@ -1,6 +1,6 @@
 var less = {
     strictUnits: true,
-    strictMath: true,
+    math: 'strict-legacy',
     logLevel: 4,
     javascriptEnabled: true
 };
diff --git a/test/browser/runner-legacy-options.js b/test/browser/runner-legacy-options.js
index 66376b368..893447cef 100644
--- a/test/browser/runner-legacy-options.js
+++ b/test/browser/runner-legacy-options.js
@@ -1,6 +1,6 @@
 var less = {
     logLevel: 4,
     errorReporting: 'console',
-    strictMath: false,
+    math: 'always',
     strictUnits: false
 };
diff --git a/test/css/calc.css b/test/css/calc.css
index e8b5dcc97..9b29d7bf8 100644
--- a/test/css/calc.css
+++ b/test/css/calc.css
@@ -3,12 +3,12 @@
   root2: calc(100% - 40px);
   width: calc(50% + (25vh - 20px));
   height: calc(50% + (25vh - 20px));
-  min-height: calc((10vh) + calc(5vh));
+  min-height: calc(10vh + calc(5vh));
   foo: 3 calc(3 + 4) 11;
   bar: calc(1 + 20%);
 }
 .b {
-  one: calc(100% - (20px));
+  one: calc(100% - 20px);
   two: calc(100% - (10px + 10px));
   three: calc(100% - (3 * 1));
   four: calc(100% - (3 * 1));
diff --git a/test/css/css-3.css b/test/css/css-3.css
index 5aafe04ec..5a14773a6 100644
--- a/test/css/css-3.css
+++ b/test/css/css-3.css
@@ -73,14 +73,6 @@ p::before {
     font-size: 12px;
   }
 }
-.units {
-  font: 1.2rem/2rem;
-  font: 8vw/9vw;
-  font: 10vh/12vh;
-  font: 12vm/15vm;
-  font: 12vmin/15vmin;
-  font: 1.2ch/1.5ch;
-}
 @supports ( box-shadow: 2px 2px 2px black ) or
           ( -moz-box-shadow: 2px 2px 2px black ) {
   .outline {
diff --git a/test/css/functions.css b/test/css/functions.css
index 35803f56a..37a5022cc 100644
--- a/test/css/functions.css
+++ b/test/css/functions.css
@@ -228,4 +228,6 @@ html {
   j: 8;
   k: 1;
   /* results in void */
+  color: green;
+  color: purple;
 }
diff --git a/test/css/math/parens-division/media-math.css b/test/css/math/parens-division/media-math.css
new file mode 100644
index 000000000..0b8be1c9d
--- /dev/null
+++ b/test/css/math/parens-division/media-math.css
@@ -0,0 +1,10 @@
+@media (min-width: 17) {
+  .foo {
+    bar: 1;
+  }
+}
+@media (min-width: 16 / 9) {
+  .foo {
+    bar: 1;
+  }
+}
diff --git a/test/css/math/parens-division/mixins-args.css b/test/css/math/parens-division/mixins-args.css
new file mode 100644
index 000000000..d95021eef
--- /dev/null
+++ b/test/css/math/parens-division/mixins-args.css
@@ -0,0 +1,169 @@
+#hidden {
+  color: transparent;
+}
+#hidden1 {
+  color: transparent;
+}
+.two-args {
+  color: blue;
+  width: 10px;
+  height: 99%;
+  depth: 99%;
+  border: 2px dotted black;
+}
+.one-arg {
+  width: 15px;
+  height: 49%;
+  depth: 49%;
+}
+.no-parens {
+  width: 5px;
+  height: 49%;
+  depth: 49%;
+}
+.no-args {
+  width: 5px;
+  height: 49%;
+  depth: 49%;
+}
+.var-args {
+  width: 45;
+  height: 8%;
+  depth: 18 / 2 - 1%;
+}
+.multi-mix {
+  width: 10px;
+  height: 29%;
+  depth: 29%;
+  margin: 4;
+  padding: 5;
+}
+body {
+  padding: 30px;
+  color: #f00;
+}
+.scope-mix {
+  width: 8;
+}
+.content {
+  width: 600px;
+}
+.content .column {
+  margin: 600px;
+}
+#same-var-name {
+  radius: 5px;
+}
+#var-inside {
+  width: 10px;
+}
+.arguments {
+  border: 1px solid black;
+  width: 1px;
+}
+.arguments2 {
+  border: 0px;
+  width: 0px;
+}
+.arguments3 {
+  border: 0px;
+  width: 0px;
+}
+.arguments4 {
+  border: 0 1 2 3 4;
+  rest: 1 2 3 4;
+  width: 0;
+}
+.edge-case {
+  border: "{";
+  width: "{";
+}
+.slash-vs-math {
+  border-radius: 2px/5px;
+  border-radius: 5px/10px;
+  border-radius: 6px;
+}
+.comma-vs-semi-colon {
+  one: a;
+  two: b, c;
+  one: d, e;
+  two: f;
+  one: g;
+  one: h;
+  one: i;
+  one: j;
+  one: k;
+  two: l;
+  one: m, n;
+  one: o, p;
+  two: q;
+  one: r, s;
+  two: t;
+}
+#named-conflict {
+  four: a, 11, 12, 13;
+  four: a, 21, 22, 23;
+}
+.test-mixin-default-arg {
+  defaults: 1px 1px 1px;
+  defaults: 2px 2px 2px;
+}
+.selector {
+  margin: 2, 2, 2, 2;
+}
+.selector2 {
+  margin: 2, 2, 2, 2;
+}
+.selector3 {
+  margin: 4;
+}
+mixins-args-expand-op-1 {
+  m3: 1, 2, 3;
+}
+mixins-args-expand-op-2 {
+  m3: 4, 5, 6;
+}
+mixins-args-expand-op-3a {
+  m3: a, b, c;
+}
+mixins-args-expand-op-3b {
+  m4: 0, a, b, c;
+}
+mixins-args-expand-op-3c {
+  m4: a, b, c, 4;
+}
+mixins-args-expand-op-4a {
+  m3: a, b, c, d;
+}
+mixins-args-expand-op-4b {
+  m4: 0, a, b, c, d;
+}
+mixins-args-expand-op-4c {
+  m4: a, b, c, d, 4;
+}
+mixins-args-expand-op-5a {
+  m3: 1, 2, 3;
+}
+mixins-args-expand-op-5b {
+  m4: 0, 1, 2, 3;
+}
+mixins-args-expand-op-5c {
+  m4: 1, 2, 3, 4;
+}
+mixins-args-expand-op-6 {
+  m4: 0, 1, 2, 3;
+}
+mixins-args-expand-op-7 {
+  m4: 0, 1, 2, 3;
+}
+mixins-args-expand-op-8 {
+  m4: 1, 1.5, 2, 3;
+}
+mixins-args-expand-op-9 {
+  aa: 4 5 6 1 2 3 and again 4 5 6;
+  a4: and;
+  a8: 5;
+}
+#test-mixin-matching-when-default-2645 {
+  height: 20px;
+}
diff --git a/test/css/math/parens-division/new-division.css b/test/css/math/parens-division/new-division.css
new file mode 100644
index 000000000..7b2486d8d
--- /dev/null
+++ b/test/css/math/parens-division/new-division.css
@@ -0,0 +1,16 @@
+.units {
+  font: 1.2rem/2rem;
+  font: 8vw/9vw;
+  font: 10vh/12vh;
+  font: 12vm/15vm;
+  font: 12vmin/15vmin;
+  font: 1.2ch/1.5ch;
+}
+.math {
+  a: 2;
+  b: 2px / 2;
+  c: 1px;
+  d: 1px;
+  e: 4px / 2;
+  f: 2px;
+}
diff --git a/test/css/math/parens-division/parens.css b/test/css/math/parens-division/parens.css
new file mode 100644
index 000000000..5e61728b6
--- /dev/null
+++ b/test/css/math/parens-division/parens.css
@@ -0,0 +1,37 @@
+.parens {
+  border: 2px solid black;
+  margin: 1px 3px 16 3;
+  width: 36;
+  padding: 2px 36px;
+}
+.more-parens {
+  padding: 8 4 4 4px;
+  width-all: 96;
+  width-first: 96;
+  width-keep: 96;
+  height: calc(100% + (25vh - 20px));
+  height-keep: 113;
+  height-all: 113;
+  height-parts: 113;
+  margin-keep: 12;
+  margin-parts: 12;
+  margin-all: 12;
+  border-radius-keep: 8px / 4 + 3px;
+  border-radius-parts: 8px / 7px;
+  border-radius-all: 5px;
+}
+.negative {
+  neg-var: -1;
+  neg-var-paren: -1;
+}
+.nested-parens {
+  width: 71;
+  height: 6;
+}
+.mixed-units {
+  margin: 2px 4em 1 5pc;
+  padding: 6px 1em 2px 2;
+}
+.test-false-negatives {
+  a: (;
+}
diff --git a/test/css/strict-math/css.css b/test/css/math/strict-legacy/css.css
similarity index 100%
rename from test/css/strict-math/css.css
rename to test/css/math/strict-legacy/css.css
diff --git a/test/css/math/strict-legacy/media-math.css b/test/css/math/strict-legacy/media-math.css
new file mode 100644
index 000000000..1d2452a0a
--- /dev/null
+++ b/test/css/math/strict-legacy/media-math.css
@@ -0,0 +1,10 @@
+@media (min-width: 16 + 1) {
+  .foo {
+    bar: 1;
+  }
+}
+@media (min-width: 16 / 9) {
+  .foo {
+    bar: 1;
+  }
+}
diff --git a/test/css/strict-math/mixins-args.css b/test/css/math/strict-legacy/mixins-args.css
similarity index 100%
rename from test/css/strict-math/mixins-args.css
rename to test/css/math/strict-legacy/mixins-args.css
diff --git a/test/css/strict-math/parens.css b/test/css/math/strict-legacy/parens.css
similarity index 88%
rename from test/css/strict-math/parens.css
rename to test/css/math/strict-legacy/parens.css
index 0e8cc7c8f..f880872fb 100644
--- a/test/css/strict-math/parens.css
+++ b/test/css/math/strict-legacy/parens.css
@@ -4,11 +4,15 @@
   width: 36;
   padding: 2px 36px;
 }
+.in-function {
+  value: 2 + 1;
+}
 .more-parens {
   padding: 8 4 4 4px;
   width-all: 96;
   width-first: 16 * 6;
   width-keep: (4 * 4) * 6;
+  height: calc(100% + (25vh - 20px));
   height-keep: (7 * 7) + (8 * 8);
   height-all: 113;
   height-parts: 49 + 64;
@@ -21,7 +25,7 @@
 }
 .negative {
   neg-var: -1;
-  neg-var-paren: -(1);
+  neg-var-paren: -1;
 }
 .nested-parens {
   width: 2 * (4 * (2 + (1 + 6))) - 1;
diff --git a/test/css/math/strict/css.css b/test/css/math/strict/css.css
new file mode 100644
index 000000000..633640781
--- /dev/null
+++ b/test/css/math/strict/css.css
@@ -0,0 +1,95 @@
+@charset "utf-8";
+div {
+  color: black;
+}
+div {
+  width: 99%;
+}
+* {
+  min-width: 45em;
+}
+h1,
+h2 > a > p,
+h3 {
+  color: none;
+}
+div.class {
+  color: blue;
+}
+div#id {
+  color: green;
+}
+.class#id {
+  color: purple;
+}
+.one.two.three {
+  color: grey;
+}
+@media print {
+  * {
+    font-size: 3em;
+  }
+}
+@media screen {
+  * {
+    font-size: 10px;
+  }
+}
+@font-face {
+  font-family: 'Garamond Pro';
+}
+a:hover,
+a:link {
+  color: #999;
+}
+p,
+p:first-child {
+  text-transform: none;
+}
+q:lang(no) {
+  quotes: none;
+}
+p + h1 {
+  font-size: 2.2em;
+}
+#shorthands {
+  border: 1px solid #000;
+  font: 12px/16px Arial;
+  font: 100%/16px Arial;
+  margin: 1px 0;
+  padding: 0 auto;
+}
+#more-shorthands {
+  margin: 0;
+  padding: 1px 0 2px 0;
+  font: normal small / 20px 'Trebuchet MS', Verdana, sans-serif;
+  font: 0/0 a;
+  border-radius: 5px / 10px;
+}
+.misc {
+  -moz-border-radius: 2px;
+  display: -moz-inline-stack;
+  width: 0.1em;
+  background-color: #009998;
+  background: -webkit-gradient(linear, left top, left bottom, from(red), to(blue));
+  margin: ;
+  filter: alpha(opacity=100);
+  width: auto\9;
+}
+.misc .nested-multiple {
+  multiple-semi-colons: yes;
+}
+#important {
+  color: red !important;
+  width: 100%!important;
+  height: 20px ! important;
+}
+@font-face {
+  font-family: font-a;
+}
+@font-face {
+  font-family: font-b;
+}
+.æøå {
+  margin: 0;
+}
diff --git a/test/css/math/strict/media-math.css b/test/css/math/strict/media-math.css
new file mode 100644
index 000000000..1d2452a0a
--- /dev/null
+++ b/test/css/math/strict/media-math.css
@@ -0,0 +1,10 @@
+@media (min-width: 16 + 1) {
+  .foo {
+    bar: 1;
+  }
+}
+@media (min-width: 16 / 9) {
+  .foo {
+    bar: 1;
+  }
+}
diff --git a/test/css/math/strict/mixins-args.css b/test/css/math/strict/mixins-args.css
new file mode 100644
index 000000000..82a3fd14b
--- /dev/null
+++ b/test/css/math/strict/mixins-args.css
@@ -0,0 +1,169 @@
+#hidden {
+  color: transparent;
+}
+#hidden1 {
+  color: transparent;
+}
+.two-args {
+  color: blue;
+  width: 10px;
+  height: 99%;
+  depth: 100% - 1%;
+  border: 2px dotted black;
+}
+.one-arg {
+  width: 15px;
+  height: 49%;
+  depth: 50% - 1%;
+}
+.no-parens {
+  width: 5px;
+  height: 49%;
+  depth: 50% - 1%;
+}
+.no-args {
+  width: 5px;
+  height: 49%;
+  depth: 50% - 1%;
+}
+.var-args {
+  width: 45;
+  height: 8%;
+  depth: 18 / 2 - 1%;
+}
+.multi-mix {
+  width: 10px;
+  height: 29%;
+  depth: 30% - 1%;
+  margin: 4;
+  padding: 5;
+}
+body {
+  padding: 30px;
+  color: #f00;
+}
+.scope-mix {
+  width: 8;
+}
+.content {
+  width: 600px;
+}
+.content .column {
+  margin: 600px;
+}
+#same-var-name {
+  radius: 5px;
+}
+#var-inside {
+  width: 10px;
+}
+.arguments {
+  border: 1px solid black;
+  width: 1px;
+}
+.arguments2 {
+  border: 0px;
+  width: 0px;
+}
+.arguments3 {
+  border: 0px;
+  width: 0px;
+}
+.arguments4 {
+  border: 0 1 2 3 4;
+  rest: 1 2 3 4;
+  width: 0;
+}
+.edge-case {
+  border: "{";
+  width: "{";
+}
+.slash-vs-math {
+  border-radius: 2px/5px;
+  border-radius: 5px/10px;
+  border-radius: 6px;
+}
+.comma-vs-semi-colon {
+  one: a;
+  two: b, c;
+  one: d, e;
+  two: f;
+  one: g;
+  one: h;
+  one: i;
+  one: j;
+  one: k;
+  two: l;
+  one: m, n;
+  one: o, p;
+  two: q;
+  one: r, s;
+  two: t;
+}
+#named-conflict {
+  four: a, 11, 12, 13;
+  four: a, 21, 22, 23;
+}
+.test-mixin-default-arg {
+  defaults: 1px 1px 1px;
+  defaults: 2px 2px 2px;
+}
+.selector {
+  margin: 2, 2, 2, 2;
+}
+.selector2 {
+  margin: 2, 2, 2, 2;
+}
+.selector3 {
+  margin: 4;
+}
+mixins-args-expand-op-1 {
+  m3: 1, 2, 3;
+}
+mixins-args-expand-op-2 {
+  m3: 4, 5, 6;
+}
+mixins-args-expand-op-3a {
+  m3: a, b, c;
+}
+mixins-args-expand-op-3b {
+  m4: 0, a, b, c;
+}
+mixins-args-expand-op-3c {
+  m4: a, b, c, 4;
+}
+mixins-args-expand-op-4a {
+  m3: a, b, c, d;
+}
+mixins-args-expand-op-4b {
+  m4: 0, a, b, c, d;
+}
+mixins-args-expand-op-4c {
+  m4: a, b, c, d, 4;
+}
+mixins-args-expand-op-5a {
+  m3: 1, 2, 3;
+}
+mixins-args-expand-op-5b {
+  m4: 0, 1, 2, 3;
+}
+mixins-args-expand-op-5c {
+  m4: 1, 2, 3, 4;
+}
+mixins-args-expand-op-6 {
+  m4: 0, 1, 2, 3;
+}
+mixins-args-expand-op-7 {
+  m4: 0, 1, 2, 3;
+}
+mixins-args-expand-op-8 {
+  m4: 1, 1.5, 2, 3;
+}
+mixins-args-expand-op-9 {
+  aa: 4 5 6 1 2 3 and again 4 5 6;
+  a4: and;
+  a8: 5;
+}
+#test-mixin-matching-when-default-2645 {
+  height: 20px;
+}
diff --git a/test/css/math/strict/parens.css b/test/css/math/strict/parens.css
new file mode 100644
index 000000000..f7b8f9776
--- /dev/null
+++ b/test/css/math/strict/parens.css
@@ -0,0 +1,37 @@
+.parens {
+  border: 2px solid black;
+  margin: 1px 3px 16 3;
+  width: 36;
+  padding: 2px 36px;
+}
+.more-parens {
+  padding: 8 4 4 4px;
+  width-all: 96;
+  width-first: 16 * 6;
+  width-keep: 16 * 6;
+  height: calc(100% + (25vh - 20px));
+  height-keep: 49 + 64;
+  height-all: 113;
+  height-parts: 49 + 64;
+  margin-keep: 20 - 8;
+  margin-parts: 20 - 8;
+  margin-all: 12;
+  border-radius-keep: 4px * 2 / 4 + 3px;
+  border-radius-parts: 8px / 7px;
+  border-radius-all: 5px;
+}
+.negative {
+  neg-var: -1;
+  neg-var-paren: -1;
+}
+.nested-parens {
+  width: 2 * 36 - 1;
+  height: 5 + 1;
+}
+.mixed-units {
+  margin: 2px 4em 1 5pc;
+  padding: 6px 1em 2px 2;
+}
+.test-false-negatives {
+  a: (;
+}
diff --git a/test/css/no-strict-math/no-sm-operations.css b/test/css/no-strict-math/no-sm-operations.css
index 00c55660b..f720ffbf3 100644
--- a/test/css/no-strict-math/no-sm-operations.css
+++ b/test/css/no-strict-math/no-sm-operations.css
@@ -13,3 +13,6 @@
 .named-colors-in-expressions-barred {
   a: a;
 }
+.division {
+  value: 2px;
+}
diff --git a/test/index.js b/test/index.js
index 7c1d314c5..24b9f961f 100644
--- a/test/index.js
+++ b/test/index.js
@@ -9,7 +9,6 @@ lessTester.prepBomTest();
 var testMap = [
     [{}, 'namespacing/'],
     [{
-        strictMath: false, 
         relativeUrls: true, 
         silent: true, 
         javascriptEnabled: true,
@@ -17,24 +16,32 @@ var testMap = [
         ieCompat: true
     }],
     [{
-        strictMath: true,
+        math: 'strict-legacy',
         ieCompat: true
-    }, 'strict-math/'],
+    }, 'math/strict-legacy/'],
+    [{
+        math: 'parens'
+    }, 'math/strict/'],
+    [{
+        math: 'parens-division'
+    }, 'math/parens-division/'],
+    // Use legacy strictMath: true here to demonstrate it still works
     [{strictMath: true, strictUnits: true, javascriptEnabled: true}, 'errors/',
         lessTester.testErrors, null],
-    [{strictMath: true, strictUnits: true, javascriptEnabled: false}, 'no-js-errors/',
+
+    [{math: 'strict', strictUnits: true, javascriptEnabled: false}, 'no-js-errors/',
         lessTester.testErrors, null],
-    [{strictMath: true, dumpLineNumbers: 'comments'}, 'debug/', null,
+    [{math: 'strict', dumpLineNumbers: 'comments'}, 'debug/', null,
         function(name) { return name + '-comments'; }],
-    [{strictMath: true, dumpLineNumbers: 'mediaquery'}, 'debug/', null,
+    [{math: 'strict', dumpLineNumbers: 'mediaquery'}, 'debug/', null,
         function(name) { return name + '-mediaquery'; }],
-    [{strictMath: true, dumpLineNumbers: 'all'}, 'debug/', null,
+    [{math: 'strict', dumpLineNumbers: 'all'}, 'debug/', null,
         function(name) { return name + '-all'; }],
-    [{strictMath: true, relativeUrls: false, rootpath: 'folder (1)/'}, 'static-urls/'],
-    [{strictMath: true, compress: true}, 'compression/'],
-    [{strictMath: false, strictUnits: true}, 'strict-units/'],
+    [{math: 'strict', relativeUrls: false, rootpath: 'folder (1)/'}, 'static-urls/'],
+    [{math: 'strict', compress: true}, 'compression/'],
+    [{math: 0, strictUnits: true}, 'strict-units/'],
     [{}, 'legacy/'],
-    [{strictMath: true, strictUnits: true, sourceMap: true, globalVars: true }, 'sourcemaps/',
+    [{math: 'strict', strictUnits: true, sourceMap: true, globalVars: true }, 'sourcemaps/',
         lessTester.testSourcemap, null, null,
         function(filename, type, baseFolder) {
             if (type === 'vars') {
@@ -42,7 +49,7 @@ var testMap = [
             }
             return path.join('test/sourcemaps', filename) + '.json';
         }],
-    [{strictMath: true, strictUnits: true, sourceMap: {sourceMapFileInline: true}},
+    [{math: 'strict', strictUnits: true, sourceMap: {sourceMapFileInline: true}},
         'sourcemaps-empty/', lessTester.testEmptySourcemap],
     [{globalVars: true, banner: '/**\n  * Test\n  */\n'}, 'globalVars/',
         null, null, null, function(name, type, baseFolder) { return path.join(baseFolder, name) + '.json'; }],
@@ -62,7 +69,7 @@ testMap.forEach(function(args) {
     lessTester.runTestSet.apply(lessTester, args)
 });
 lessTester.testSyncronous({syncImport: true}, 'import');
-lessTester.testSyncronous({syncImport: true}, 'strict-math/css');
+lessTester.testSyncronous({syncImport: true}, 'math/strict-legacy/css');
 lessTester.testNoOptions();
 lessTester.testJSImport();
 lessTester.finished();
diff --git a/test/less/css-3.less b/test/less/css-3.less
index 9f206791b..999e8019b 100644
--- a/test/less/css-3.less
+++ b/test/less/css-3.less
@@ -79,15 +79,6 @@ p::before {
   }
 }
 
-.units {
-  font: 1.2rem/2rem;
-  font: 8vw/9vw;
-  font: 10vh/12vh;
-  font: 12vm/15vm;
-  font: 12vmin/15vmin;
-  font: 1.2ch/1.5ch;
-}
-
 @supports ( box-shadow: 2px 2px 2px black ) or
           ( -moz-box-shadow: 2px 2px 2px black ) {
   .outline {
diff --git a/test/less/functions.less b/test/less/functions.less
index 0228bf0cb..8057a6649 100644
--- a/test/less/functions.less
+++ b/test/less/functions.less
@@ -263,5 +263,17 @@ html {
   j: if(not(true) and true, 6, 8);
   k: if(true or true, 1);
 
-  if(false, {g: 7}); /* results in void */
+  if((false), {g: 7}); /* results in void */
+
+  @conditional: if((true), {
+    color: green;
+  }, {});
+  @conditional();
+
+  @falsey: if((false), {
+    color: orange;
+  }, {
+    color: purple;
+  });
+  @falsey();
 }
diff --git a/test/less/math/parens-division/media-math.less b/test/less/math/parens-division/media-math.less
new file mode 100644
index 000000000..b3df9118e
--- /dev/null
+++ b/test/less/math/parens-division/media-math.less
@@ -0,0 +1,9 @@
+@var: 16;
+
+@media (min-width: @var + 1) {
+  .foo { bar: 1; }
+}
+
+@media (min-width: @var / 9) {
+  .foo { bar: 1; }
+}
\ No newline at end of file
diff --git a/test/less/math/parens-division/mixins-args.less b/test/less/math/parens-division/mixins-args.less
new file mode 100644
index 000000000..7b1bef0e0
--- /dev/null
+++ b/test/less/math/parens-division/mixins-args.less
@@ -0,0 +1,264 @@
+.mixin (@a: 1px, @b: 50%) {
+  width: (@a * 5);
+  height: (@b - 1%);
+  depth: @b - 1%;
+}
+
+.mixina (@style, @width, @color: black) {
+    border: @width @style @color;
+}
+
+.mixiny
+(@a: 0, @b: 0) {
+  margin: @a;
+  padding: @b;
+}
+
+.hidden() {
+  color: transparent; // asd
+}
+
+#hidden {
+  .hidden;
+}
+
+#hidden1 {
+  .hidden();
+}
+
+.two-args {
+  color: blue;
+  .mixin(2px, 100%);
+  .mixina(dotted, 2px);
+}
+
+.one-arg {
+  .mixin(3px);
+}
+
+.no-parens {
+  .mixin;
+}
+
+.no-args {
+  .mixin();
+}
+
+.var-args {
+  @var: 9;
+  .mixin(@var, (@var * 2) / 2);
+}
+
+.multi-mix {
+  .mixin(2px, 30%);
+  .mixiny(4, 5);
+}
+
+.maxa(@arg1: 10, @arg2: #f00) {
+  padding: (@arg1 * 2px);
+  color: @arg2;
+}
+
+body {
+  .maxa(15);
+}
+
+@glob: 5;
+.global-mixin(@a:2) {
+  width: (@glob + @a);
+}
+
+.scope-mix {
+  .global-mixin(3);
+}
+
+.nested-ruleset (@width: 200px) {
+    width: @width;
+    .column { margin: @width; }
+}
+.content {
+    .nested-ruleset(600px);
+}
+
+//
+
+.same-var-name2(@radius) {
+  radius: @radius;
+}
+.same-var-name(@radius) {
+  .same-var-name2(@radius);
+}
+#same-var-name {
+  .same-var-name(5px);
+}
+
+//
+
+.var-inside () {
+    @var: 10px;
+    width: @var;
+}
+#var-inside { .var-inside; }
+
+.mixin-arguments (@width: 0px, ...) {
+    border: @arguments;
+    width: @width;
+}
+
+.arguments {
+    .mixin-arguments(1px, solid, black);
+}
+.arguments2 {
+    .mixin-arguments();
+}
+.arguments3 {
+    .mixin-arguments;
+}
+
+.mixin-arguments2 (@width, @rest...) {
+    border: @arguments;
+    rest: @rest;
+    width: @width;
+}
+.arguments4 {
+    .mixin-arguments2(0, 1, 2, 3, 4);
+}
+
+// Edge cases
+
+.edge-case {
+    .mixin-arguments("{");
+}
+
+// Division vs. Literal Slash
+.border-radius(@r: 2px/5px) {
+  border-radius: @r;
+}
+.slash-vs-math {
+  .border-radius();
+  .border-radius(5px/10px);
+  .border-radius((3px * 2));
+}
+// semi-colon vs comma for delimiting
+
+.mixin-takes-one(@a) {
+    one: @a;
+}
+
+.mixin-takes-two(@a; @b) {
+    one: @a;
+    two: @b;
+}
+
+.comma-vs-semi-colon {
+    .mixin-takes-two(@a : a; @b : b, c);
+    .mixin-takes-two(@a : d, e; @b : f);
+    .mixin-takes-one(@a: g);
+    .mixin-takes-one(@a : h;);
+    .mixin-takes-one(i);
+    .mixin-takes-one(j;);
+    .mixin-takes-two(k, l);
+    .mixin-takes-one(m, n;);
+    .mixin-takes-two(o, p; q);
+    .mixin-takes-two(r, s; t;);
+}
+
+.mixin-conflict(@a:defA, @b:defB, @c:defC) {
+  three: @a, @b, @c;
+}
+
+.mixin-conflict(@a:defA, @b:defB, @c:defC, @d:defD) {
+  four: @a, @b, @c, @d;
+}
+
+#named-conflict {
+  .mixin-conflict(11, 12, 13, @a:a);
+  .mixin-conflict(@a:a, 21, 22, 23);
+}
+@a: 3px;
+.mixin-default-arg(@a: 1px, @b: @a, @c: @b) {
+  defaults: 1px 1px 1px;
+  defaults: 2px 2px 2px;
+}
+
+.test-mixin-default-arg {
+  .mixin-default-arg();
+  .mixin-default-arg(2px);
+}
+
+.mixin-comma-default1(@color; @padding; @margin: 2, 2, 2, 2) {
+  margin: @margin;
+}
+.selector {
+  .mixin-comma-default1(#33acfe; 4);
+}
+.mixin-comma-default2(@margin: 2, 2, 2, 2;) {
+  margin: @margin;
+}
+.selector2 {
+  .mixin-comma-default2();
+}
+.mixin-comma-default3(@margin: 2, 2, 2, 2) {
+  margin: @margin;
+}
+.selector3 {
+  .mixin-comma-default3(4,2,2,2);
+}
+
+.test-calling-one-arg-mixin(@a) {
+}
+
+.test-calling-one-arg-mixin(@a, @b, @rest...) {
+}
+
+div {
+  .test-calling-one-arg-mixin(1);
+}
+
+mixins-args-expand-op- {
+  @x: 1, 2, 3;
+  @y: 4  5  6;
+
+  &1 {.m3(@x...)}
+  &2 {.m3(@y...)}
+  &3 {.wr(a, b, c)}
+  &4 {.wr(a; b; c, d)}
+  &5 {.wr(@x...)}
+  &6 {.m4(0; @x...)}
+  &7 {.m4(@x..., @a: 0)}
+  &8 {.m4(@b: 1.5; @x...)}
+  &9 {.aa(@y, @x..., and again, @y...)}
+
+  .m3(@a, @b, @c) {
+    m3: @a, @b, @c;
+  }
+
+  .m4(@a, @b, @c, @d) {
+    m4: @a, @b, @c, @d;
+  }
+
+  .wr(@a...) {
+    &a {.m3(@a...)}
+    &b {.m4(0, @a...)}
+    &c {.m4(@a..., 4)}
+  }
+
+  .aa(@a...) {
+    aa: @a;
+    a4: extract(@a, 5);
+    a8: extract(@a, 8);
+  }
+}
+#test-mixin-matching-when-default-2645 {
+  .mixin(@height) {
+    height: @height;
+  }
+
+  .mixin(@width, @height: 10px) {
+    width: @width;
+
+    .mixin(@height: @height);
+  }
+
+  .mixin(@height: 20px);
+}
\ No newline at end of file
diff --git a/test/less/math/parens-division/new-division.less b/test/less/math/parens-division/new-division.less
new file mode 100644
index 000000000..b81c26e26
--- /dev/null
+++ b/test/less/math/parens-division/new-division.less
@@ -0,0 +1,17 @@
+.units {
+  font: 1.2rem/2rem;
+  font: 8vw/9vw;
+  font: 10vh/12vh;
+  font: 12vm/15vm;
+  font: 12vmin/15vmin;
+  font: 1.2ch/1.5ch;
+}
+
+.math {
+  a: 1 + 1;
+  b: 2px / 2;
+  c: 2px ./ 2;
+  d: (10px / 10px);
+  e: ((16px ./ 2) / 2) / 2;
+  f: ((16px ./ 2) / 2) ./ 2;
+}
\ No newline at end of file
diff --git a/test/less/strict-math/parens.less b/test/less/math/parens-division/parens.less
similarity index 94%
rename from test/less/strict-math/parens.less
rename to test/less/math/parens-division/parens.less
index eeef34481..becbd04e6 100644
--- a/test/less/strict-math/parens.less
+++ b/test/less/math/parens-division/parens.less
@@ -12,6 +12,7 @@
   width-all: ((@var * @var) * 6);
   width-first: ((@var * @var)) * 6;
   width-keep: (@var * @var) * 6;
+  height: calc(100% + (25vh - 20px));
   height-keep: (7 * 7) + (8 * 8);
   height-all: ((7 * 7) + (8 * 8));
   height-parts: ((7 * 7)) + ((8 * 8));
@@ -21,7 +22,7 @@
   border-radius-keep: 4px * (1 + 1) / @var + 3px;
   border-radius-parts: ((4px * (1 + 1))) / ((@var + 3px));
   border-radius-all: (4px * (1 + 1) / @var + 3px);
-  //margin: (6 * 6)px;
+  // margin: (6 * 6)px;
 }
 
 .negative {
diff --git a/test/less/strict-math/css.less b/test/less/math/strict-legacy/css.less
similarity index 100%
rename from test/less/strict-math/css.less
rename to test/less/math/strict-legacy/css.less
diff --git a/test/less/math/strict-legacy/media-math.less b/test/less/math/strict-legacy/media-math.less
new file mode 100644
index 000000000..b3df9118e
--- /dev/null
+++ b/test/less/math/strict-legacy/media-math.less
@@ -0,0 +1,9 @@
+@var: 16;
+
+@media (min-width: @var + 1) {
+  .foo { bar: 1; }
+}
+
+@media (min-width: @var / 9) {
+  .foo { bar: 1; }
+}
\ No newline at end of file
diff --git a/test/less/strict-math/mixins-args.less b/test/less/math/strict-legacy/mixins-args.less
similarity index 100%
rename from test/less/strict-math/mixins-args.less
rename to test/less/math/strict-legacy/mixins-args.less
diff --git a/test/less/math/strict-legacy/parens.less b/test/less/math/strict-legacy/parens.less
new file mode 100644
index 000000000..012142545
--- /dev/null
+++ b/test/less/math/strict-legacy/parens.less
@@ -0,0 +1,50 @@
+.parens {
+  @var: 1px;
+  border: (@var * 2) solid black;
+  margin: (@var * 1) (@var + 2) (4 * 4) 3;
+  width: (6 * 6);
+  padding: 2px (6 * 6px);
+}
+
+.in-function {
+  value: min((1 + 1)) + 1;
+}
+
+.more-parens {
+  @var: (2 * 2);
+  padding: (2 * @var) 4 4 (@var * 1px);
+  width-all: ((@var * @var) * 6);
+  width-first: ((@var * @var)) * 6;
+  width-keep: (@var * @var) * 6;
+  height: calc(100% + (25vh - 20px));
+  height-keep: (7 * 7) + (8 * 8);
+  height-all: ((7 * 7) + (8 * 8));
+  height-parts: ((7 * 7)) + ((8 * 8));
+  margin-keep: (4 * (5 + 5) / 2) - (@var * 2);
+  margin-parts: ((4 * (5 + 5) / 2)) - ((@var * 2));
+  margin-all: ((4 * (5 + 5) / 2) + (-(@var * 2)));
+  border-radius-keep: 4px * (1 + 1) / @var + 3px;
+  border-radius-parts: ((4px * (1 + 1))) / ((@var + 3px));
+  border-radius-all: (4px * (1 + 1) / @var + 3px);
+  // margin: (6 * 6)px;
+}
+
+.negative {
+  @var: 1;
+  neg-var: -@var; // -1 ?
+  neg-var-paren: -(@var); // -(1) ?
+}
+
+.nested-parens {
+  width: 2 * (4 * (2 + (1 + 6))) - 1;
+  height: ((2 + 3) * (2 + 3) / (9 - 4)) + 1;
+}
+
+.mixed-units {
+  margin: 2px 4em 1 5pc;
+  padding: (2px + 4px) 1em 2px 2;
+}
+
+.test-false-negatives {
+  a: ~"(";
+}
diff --git a/test/less/math/strict/css.less b/test/less/math/strict/css.less
new file mode 100644
index 000000000..0cdebae89
--- /dev/null
+++ b/test/less/math/strict/css.less
@@ -0,0 +1,108 @@
+@charset "utf-8";
+div { color: black; }
+div { width: 99%; }
+
+* {
+  min-width: 45em;
+}
+
+h1, h2 > a > p, h3 {
+  color: none;
+}
+
+div.class {
+  color: blue;
+}
+
+div#id {
+  color: green;
+}
+
+.class#id {
+  color: purple;
+}
+
+.one.two.three {
+  color: grey;
+}
+
+@media print {
+  * {
+    font-size: 3em;
+  }
+}
+
+@media screen {
+  * {
+    font-size: 10px;
+  }
+}
+
+@font-face {
+  font-family: 'Garamond Pro';
+}
+
+a:hover, a:link {
+  color: #999;
+}
+
+p, p:first-child {
+  text-transform: none;
+}
+
+q:lang(no) {
+  quotes: none;
+}
+
+p + h1 {
+  font-size: +2.2em;
+}
+
+#shorthands {
+  border: 1px solid #000;
+  font: 12px/16px Arial;
+  font: 100%/16px Arial;
+  margin: 1px 0;
+  padding: 0 auto;
+}
+
+#more-shorthands {
+  margin: 0;
+  padding: 1px 0 2px 0;
+  font: normal small/20px 'Trebuchet MS', Verdana, sans-serif;
+  font: 0/0 a;
+  border-radius: 5px / 10px;
+}
+
+.misc {
+  -moz-border-radius: 2px;
+  display: -moz-inline-stack;
+  width: .1em;
+  background-color: #009998;
+  background: -webkit-gradient(linear, left top, left bottom, from(red), to(blue));
+  margin: ;
+  .nested-multiple {
+    multiple-semi-colons: yes;;;;;;
+  };
+  filter: alpha(opacity=100);
+  width: auto\9;
+}
+
+#important {
+  color: red !important;
+  width: 100%!important;
+  height: 20px ! important;
+}
+
+.def-font(@name) {
+    @font-face {
+        font-family: @name
+    }
+}
+
+.def-font(font-a);
+.def-font(font-b);
+
+.æøå {
+  margin: 0;
+}
diff --git a/test/less/math/strict/media-math.less b/test/less/math/strict/media-math.less
new file mode 100644
index 000000000..b3df9118e
--- /dev/null
+++ b/test/less/math/strict/media-math.less
@@ -0,0 +1,9 @@
+@var: 16;
+
+@media (min-width: @var + 1) {
+  .foo { bar: 1; }
+}
+
+@media (min-width: @var / 9) {
+  .foo { bar: 1; }
+}
\ No newline at end of file
diff --git a/test/less/math/strict/mixins-args.less b/test/less/math/strict/mixins-args.less
new file mode 100644
index 000000000..7b1bef0e0
--- /dev/null
+++ b/test/less/math/strict/mixins-args.less
@@ -0,0 +1,264 @@
+.mixin (@a: 1px, @b: 50%) {
+  width: (@a * 5);
+  height: (@b - 1%);
+  depth: @b - 1%;
+}
+
+.mixina (@style, @width, @color: black) {
+    border: @width @style @color;
+}
+
+.mixiny
+(@a: 0, @b: 0) {
+  margin: @a;
+  padding: @b;
+}
+
+.hidden() {
+  color: transparent; // asd
+}
+
+#hidden {
+  .hidden;
+}
+
+#hidden1 {
+  .hidden();
+}
+
+.two-args {
+  color: blue;
+  .mixin(2px, 100%);
+  .mixina(dotted, 2px);
+}
+
+.one-arg {
+  .mixin(3px);
+}
+
+.no-parens {
+  .mixin;
+}
+
+.no-args {
+  .mixin();
+}
+
+.var-args {
+  @var: 9;
+  .mixin(@var, (@var * 2) / 2);
+}
+
+.multi-mix {
+  .mixin(2px, 30%);
+  .mixiny(4, 5);
+}
+
+.maxa(@arg1: 10, @arg2: #f00) {
+  padding: (@arg1 * 2px);
+  color: @arg2;
+}
+
+body {
+  .maxa(15);
+}
+
+@glob: 5;
+.global-mixin(@a:2) {
+  width: (@glob + @a);
+}
+
+.scope-mix {
+  .global-mixin(3);
+}
+
+.nested-ruleset (@width: 200px) {
+    width: @width;
+    .column { margin: @width; }
+}
+.content {
+    .nested-ruleset(600px);
+}
+
+//
+
+.same-var-name2(@radius) {
+  radius: @radius;
+}
+.same-var-name(@radius) {
+  .same-var-name2(@radius);
+}
+#same-var-name {
+  .same-var-name(5px);
+}
+
+//
+
+.var-inside () {
+    @var: 10px;
+    width: @var;
+}
+#var-inside { .var-inside; }
+
+.mixin-arguments (@width: 0px, ...) {
+    border: @arguments;
+    width: @width;
+}
+
+.arguments {
+    .mixin-arguments(1px, solid, black);
+}
+.arguments2 {
+    .mixin-arguments();
+}
+.arguments3 {
+    .mixin-arguments;
+}
+
+.mixin-arguments2 (@width, @rest...) {
+    border: @arguments;
+    rest: @rest;
+    width: @width;
+}
+.arguments4 {
+    .mixin-arguments2(0, 1, 2, 3, 4);
+}
+
+// Edge cases
+
+.edge-case {
+    .mixin-arguments("{");
+}
+
+// Division vs. Literal Slash
+.border-radius(@r: 2px/5px) {
+  border-radius: @r;
+}
+.slash-vs-math {
+  .border-radius();
+  .border-radius(5px/10px);
+  .border-radius((3px * 2));
+}
+// semi-colon vs comma for delimiting
+
+.mixin-takes-one(@a) {
+    one: @a;
+}
+
+.mixin-takes-two(@a; @b) {
+    one: @a;
+    two: @b;
+}
+
+.comma-vs-semi-colon {
+    .mixin-takes-two(@a : a; @b : b, c);
+    .mixin-takes-two(@a : d, e; @b : f);
+    .mixin-takes-one(@a: g);
+    .mixin-takes-one(@a : h;);
+    .mixin-takes-one(i);
+    .mixin-takes-one(j;);
+    .mixin-takes-two(k, l);
+    .mixin-takes-one(m, n;);
+    .mixin-takes-two(o, p; q);
+    .mixin-takes-two(r, s; t;);
+}
+
+.mixin-conflict(@a:defA, @b:defB, @c:defC) {
+  three: @a, @b, @c;
+}
+
+.mixin-conflict(@a:defA, @b:defB, @c:defC, @d:defD) {
+  four: @a, @b, @c, @d;
+}
+
+#named-conflict {
+  .mixin-conflict(11, 12, 13, @a:a);
+  .mixin-conflict(@a:a, 21, 22, 23);
+}
+@a: 3px;
+.mixin-default-arg(@a: 1px, @b: @a, @c: @b) {
+  defaults: 1px 1px 1px;
+  defaults: 2px 2px 2px;
+}
+
+.test-mixin-default-arg {
+  .mixin-default-arg();
+  .mixin-default-arg(2px);
+}
+
+.mixin-comma-default1(@color; @padding; @margin: 2, 2, 2, 2) {
+  margin: @margin;
+}
+.selector {
+  .mixin-comma-default1(#33acfe; 4);
+}
+.mixin-comma-default2(@margin: 2, 2, 2, 2;) {
+  margin: @margin;
+}
+.selector2 {
+  .mixin-comma-default2();
+}
+.mixin-comma-default3(@margin: 2, 2, 2, 2) {
+  margin: @margin;
+}
+.selector3 {
+  .mixin-comma-default3(4,2,2,2);
+}
+
+.test-calling-one-arg-mixin(@a) {
+}
+
+.test-calling-one-arg-mixin(@a, @b, @rest...) {
+}
+
+div {
+  .test-calling-one-arg-mixin(1);
+}
+
+mixins-args-expand-op- {
+  @x: 1, 2, 3;
+  @y: 4  5  6;
+
+  &1 {.m3(@x...)}
+  &2 {.m3(@y...)}
+  &3 {.wr(a, b, c)}
+  &4 {.wr(a; b; c, d)}
+  &5 {.wr(@x...)}
+  &6 {.m4(0; @x...)}
+  &7 {.m4(@x..., @a: 0)}
+  &8 {.m4(@b: 1.5; @x...)}
+  &9 {.aa(@y, @x..., and again, @y...)}
+
+  .m3(@a, @b, @c) {
+    m3: @a, @b, @c;
+  }
+
+  .m4(@a, @b, @c, @d) {
+    m4: @a, @b, @c, @d;
+  }
+
+  .wr(@a...) {
+    &a {.m3(@a...)}
+    &b {.m4(0, @a...)}
+    &c {.m4(@a..., 4)}
+  }
+
+  .aa(@a...) {
+    aa: @a;
+    a4: extract(@a, 5);
+    a8: extract(@a, 8);
+  }
+}
+#test-mixin-matching-when-default-2645 {
+  .mixin(@height) {
+    height: @height;
+  }
+
+  .mixin(@width, @height: 10px) {
+    width: @width;
+
+    .mixin(@height: @height);
+  }
+
+  .mixin(@height: 20px);
+}
\ No newline at end of file
diff --git a/test/less/math/strict/parens.less b/test/less/math/strict/parens.less
new file mode 100644
index 000000000..becbd04e6
--- /dev/null
+++ b/test/less/math/strict/parens.less
@@ -0,0 +1,46 @@
+.parens {
+  @var: 1px;
+  border: (@var * 2) solid black;
+  margin: (@var * 1) (@var + 2) (4 * 4) 3;
+  width: (6 * 6);
+  padding: 2px (6 * 6px);
+}
+
+.more-parens {
+  @var: (2 * 2);
+  padding: (2 * @var) 4 4 (@var * 1px);
+  width-all: ((@var * @var) * 6);
+  width-first: ((@var * @var)) * 6;
+  width-keep: (@var * @var) * 6;
+  height: calc(100% + (25vh - 20px));
+  height-keep: (7 * 7) + (8 * 8);
+  height-all: ((7 * 7) + (8 * 8));
+  height-parts: ((7 * 7)) + ((8 * 8));
+  margin-keep: (4 * (5 + 5) / 2) - (@var * 2);
+  margin-parts: ((4 * (5 + 5) / 2)) - ((@var * 2));
+  margin-all: ((4 * (5 + 5) / 2) + (-(@var * 2)));
+  border-radius-keep: 4px * (1 + 1) / @var + 3px;
+  border-radius-parts: ((4px * (1 + 1))) / ((@var + 3px));
+  border-radius-all: (4px * (1 + 1) / @var + 3px);
+  // margin: (6 * 6)px;
+}
+
+.negative {
+  @var: 1;
+  neg-var: -@var; // -1 ?
+  neg-var-paren: -(@var); // -(1) ?
+}
+
+.nested-parens {
+  width: 2 * (4 * (2 + (1 + 6))) - 1;
+  height: ((2 + 3) * (2 + 3) / (9 - 4)) + 1;
+}
+
+.mixed-units {
+  margin: 2px 4em 1 5pc;
+  padding: (2px + 4px) 1em 2px 2;
+}
+
+.test-false-negatives {
+  a: ~"(";
+}
diff --git a/test/less/no-strict-math/no-sm-operations.less b/test/less/no-strict-math/no-sm-operations.less
index e79d05009..d4bfdb977 100644
--- a/test/less/no-strict-math/no-sm-operations.less
+++ b/test/less/no-strict-math/no-sm-operations.less
@@ -11,3 +11,6 @@
     color: green-black;
     animation: blue-change 5s infinite;
 }
+.division {
+    value: ((16px ./ 2) / 2) / 2;
+}
\ No newline at end of file