diff --git a/src/event.js b/src/event.js
index 5841aff7c..fb9727867 100644
--- a/src/event.js
+++ b/src/event.js
@@ -208,8 +208,8 @@ jQuery.event = {
 
 		var i, cur, tmp, bubbleType, ontype, handle, special,
 			eventPath = [ elem || document ],
-			type = event.type || event,
-			namespaces = event.namespace ? event.namespace.split(".") : [];
+			type = core_hasOwn.call(event, 'type') ? event.type : event,
+			namespaces = core_hasOwn.call(event, 'namespace') ? event.namespace.split(".") : [];
 
 		cur = tmp = elem = elem || document;
 
diff --git a/test/unit/event.js b/test/unit/event.js
index bde9f7f43..2bede51fa 100644
--- a/test/unit/event.js
+++ b/test/unit/event.js
@@ -2666,3 +2666,17 @@ test( "Check order of focusin/focusout events", 2, function() {
 	input.off();
 });
 
+test("make sure defining 'namespace' on String.prototype does not cause trigger() to error", function() {
+	expect(1);
+	var errored = false;
+	String.prototype.namespace = function() {
+		return "test";
+	};
+	try {
+		jQuery("<p>").trigger('foo.bar');
+	} catch( e ) {
+		errored = true;
+	}
+	equal(errored, false, 'trigger() should not have errored');
+	delete String.prototype.namespace;
+});