diff --git a/lib/coffee_script/grammar.y b/lib/coffee_script/grammar.y
index aa0a7caa..885e7562 100644
--- a/lib/coffee_script/grammar.y
+++ b/lib/coffee_script/grammar.y
@@ -183,6 +183,7 @@ rule
   | Expression '&&=' Expression       { result = OpNode.new(val[1], val[0], val[2]) }
 
   | Expression INSTANCEOF Expression  { result = OpNode.new(val[1], val[0], val[2]) }
+  | Expression IN Expression          { result = OpNode.new(val[1], val[0], val[2]) }
   ;
 
   Existence:
diff --git a/test/fixtures/execution/test_array_comprehension.coffee b/test/fixtures/execution/test_array_comprehension.coffee
index 27d04871..5fdfe1df 100644
--- a/test/fixtures/execution/test_array_comprehension.coffee
+++ b/test/fixtures/execution/test_array_comprehension.coffee
@@ -19,3 +19,7 @@ evens: for num in [1, 2, 3, 4, 5, 6] when num % 2 is 0
 
 print(evens.join(', ') is '4, 6, 8')
 
+# Make sure that the "in" operator still works.
+
+print(2 in evens)
+