diff --git a/src/core.js b/src/core.js
index 4c12150d..62e41c96 100644
--- a/src/core.js
+++ b/src/core.js
@@ -553,7 +553,7 @@ jQuery.extend = jQuery.fn.extend = function() {
 					target[ name ] = jQuery.extend( target[ name ], options[ name ] );
 
 				// Don't bring in undefined values
-				else if ( options[ name ] !== undefined )
+				else if ( options[ name ] != undefined )
 					target[ name ] = options[ name ];
 
 			}
diff --git a/test/unit/core.js b/test/unit/core.js
index f0393041..ce70be68 100644
--- a/test/unit/core.js
+++ b/test/unit/core.js
@@ -874,7 +874,7 @@ test("$.extend(Object, Object)", function() {
 	ok( typeof ret.foo != "string", "Check to make sure values equal with coersion (but not actually equal) overwrite correctly" );
 
 	var ret = jQuery.extend(true, { foo:"bar" }, { foo:null } );
-	equals( ret.foo, null, "Check to make sure values equal with coersion (but not actually equal) overwrite correctly" );
+	ok( typeof ret.foo !== 'undefined', "Make sure a null value doesn't crash with deep extend, for #1908" );
 
 	var defaults = { xnumber1: 5, xnumber2: 7, xstring1: "peter", xstring2: "pan" },
 		defaultsCopy = { xnumber1: 5, xnumber2: 7, xstring1: "peter", xstring2: "pan" },