diff --git a/test/moduleMinimizeTestCases/custom-variables/expected.css b/test/moduleMinimizeTestCases/custom-variables/expected.css
new file mode 100644
index 00000000..f975ee3f
--- /dev/null
+++ b/test/moduleMinimizeTestCases/custom-variables/expected.css
@@ -0,0 +1 @@
+:root{--foo:1px;--bar:2px}
\ No newline at end of file
diff --git a/test/moduleMinimizeTestCases/custom-variables/source.css b/test/moduleMinimizeTestCases/custom-variables/source.css
new file mode 100644
index 00000000..344f3d34
--- /dev/null
+++ b/test/moduleMinimizeTestCases/custom-variables/source.css
@@ -0,0 +1,4 @@
+:root {
+	--foo: 1px;
+	--bar: 2px;
+}
diff --git a/test/simpleTest.js b/test/simpleTest.js
index 33636ccc..407b0310 100644
--- a/test/simpleTest.js
+++ b/test/simpleTest.js
@@ -38,6 +38,9 @@ describe("simple", function() {
 	test("charset directive", "@charset \"UTF-8\";\n .class { a: b c d; }", [
 		[1, "@charset \"UTF-8\";\n .class { a: b c d; }", ""]
 	]);
+  test("custom variables", ":root {--foo: 1px;\n--bar: 2px;}", [
+    [1, ":root {--foo: 1px;\n--bar: 2px;}", ""]
+  ]);
 	testError("error formatting", ".some {\n invalid css;\n}", function(err) {
 		assert.equal(err.message, [
 			'Unknown word (2:2)',