diff --git a/package.json b/package.json
index c48e600..3e65206 100644
--- a/package.json
+++ b/package.json
@@ -15,7 +15,7 @@
     "grunt-cli": "^0.1.13",
     "grunt-contrib-concat": "^0.5.0",
     "grunt-contrib-connect": "^0.9.0",
-    "grunt-contrib-jshint": "^0.10.0",
+    "grunt-contrib-jshint": "^1.1.0",
     "grunt-contrib-sass": "^0.8.1",
     "grunt-contrib-watch": "^0.6.1",
     "grunt-jscs": "^1.1.0",
diff --git a/src/SessionCipher.js b/src/SessionCipher.js
index 5c6b914..2727193 100644
--- a/src/SessionCipher.js
+++ b/src/SessionCipher.js
@@ -185,7 +185,7 @@ SessionCipher.prototype = {
       }.bind(this));
   },
   doDecryptWhisperMessage: function(messageBytes, session) {
-    if (!messageBytes instanceof ArrayBuffer) {
+    if (!(messageBytes instanceof ArrayBuffer)) {
         throw new Error("Expected messageBytes to be an ArrayBuffer");
     }
     var version = (new Uint8Array(messageBytes))[0];