diff --git a/lib/coffee-script/grammar.js b/lib/coffee-script/grammar.js
index 5529c41d..f116c108 100644
--- a/lib/coffee-script/grammar.js
+++ b/lib/coffee-script/grammar.js
@@ -141,7 +141,7 @@
       }), o('Value Accessor', function() {
         return $1.add($2);
       }), o('Invocation Accessor', function() {
-        return new Value($1, [$2]);
+        return new Value($1, [].concat($2));
       }), o('ThisProperty')
     ],
     Assignable: [
diff --git a/src/grammar.coffee b/src/grammar.coffee
index 035e1680..2a6838c1 100644
--- a/src/grammar.coffee
+++ b/src/grammar.coffee
@@ -218,7 +218,7 @@ grammar =
   SimpleAssignable: [
     o 'Identifier',                             -> new Value $1
     o 'Value Accessor',                         -> $1.add $2
-    o 'Invocation Accessor',                    -> new Value $1, [$2]
+    o 'Invocation Accessor',                    -> new Value $1, [].concat $2
     o 'ThisProperty'
   ]