diff --git a/package.json b/package.json
index 9f37b25..824ead8 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "momentumengine",
-  "version": "0.5.0",
+  "version": "0.5.1",
   "description": "An ES6 game and animation engine.",
   "main": "src/es6.js",
   "repository": {
diff --git a/src/classes/keyboardinput.js b/src/classes/keyboardinput.js
index b539c63..f26e138 100644
--- a/src/classes/keyboardinput.js
+++ b/src/classes/keyboardinput.js
@@ -150,7 +150,7 @@ class KeyboardInput {
 
 
     _keyUpHandler (event) {
-        wasReleased[event.keyCode = true];
+        wasReleased[event.keyCode] = true;
         this._keyState[event.keyCode] = false;
     }