diff --git a/source-map-support.js b/source-map-support.js
index 5074dc5..b312e62 100644
--- a/source-map-support.js
+++ b/source-map-support.js
@@ -14,6 +14,9 @@ var fileContentsCache = {};
 // Maps a file path to a source map for that file
 var sourceMapCache = {};
 
+// Regex for detecting source maps
+var reSourceMap = /^data:application\/json[^,]+base64,/;
+
 function isInBrowser() {
   return ((typeof window !== 'undefined') && (typeof XMLHttpRequest === 'function'));
 }
@@ -97,10 +100,10 @@ function retrieveSourceMap(source) {
 
   // Read the contents of the source map
   var sourceMapData;
-  var dataUrlPrefix = "data:application/json;base64,";
-  if (sourceMappingURL.slice(0, dataUrlPrefix.length).toLowerCase() == dataUrlPrefix) {
+  if (reSourceMap.test(sourceMappingURL)) {
     // Support source map URL as a data url
-    sourceMapData = new Buffer(sourceMappingURL.slice(dataUrlPrefix.length), "base64").toString();
+    var rawData = sourceMappingURL.slice(sourceMappingURL.indexOf(',') + 1);
+    sourceMapData = new Buffer(rawData, "base64").toString();
     sourceMappingURL = null;
   } else {
     // Support source map URLs relative to the source URL
diff --git a/test.js b/test.js
index 8eab1c4..bd25f92 100644
--- a/test.js
+++ b/test.js
@@ -391,3 +391,27 @@ it('missing source maps should also be cached', function(done) {
     '1', // The retrieval should only be attempted once
   ]);
 });
+
+/* The following test duplicates some of the code in
+ * `compareStackTrace` but appends a charset to the
+ * source mapping url.
+ */
+it('finds source maps with charset specified', function() {
+  var sourceMap = createMultiLineSourceMap()
+  var source = [ 'throw new Error("test");' ];
+  var expected = [
+    'Error: test',
+    /^    at Object\.exports\.test \(.*\/line1\.js:1001:101\)$/
+  ];
+
+  fs.writeFileSync('.generated.js', 'exports.test = function() {' +
+    source.join('\n') + '};//@ sourceMappingURL=data:application/json;charset=utf8;base64,' +
+    new Buffer(sourceMap.toString()).toString('base64'));
+  try {
+    delete require.cache[require.resolve('./.generated')];
+    require('./.generated').test();
+  } catch (e) {
+    compareLines(e.stack.split('\n'), expected);
+  }
+  fs.unlinkSync('.generated.js');
+});