diff --git a/src/event.js b/src/event.js
index 65b59523e..00bef8472 100644
--- a/src/event.js
+++ b/src/event.js
@@ -470,8 +470,8 @@ jQuery.event = {
 		}
 
 		// Add which for key events
-		if ( !event.which && ((event.charCode || event.charCode === 0) ? event.charCode : event.keyCode) ) {
-			event.which = event.charCode || event.keyCode;
+		if ( event.which == null && (event.charCode != null || event.charCode != null) ) {
+			event.which = event.charCode != null ? event.charCode : event.keyCode;
 		}
 
 		// Add metaKey to non-Mac browsers (use ctrl for PC's and Meta for Macs)