Index: test/unit/core.js
===================================================================
--- test/unit/core.js	(revision 3483)
+++ test/unit/core.js	(working copy)
@@ -926,7 +926,7 @@
 });
 
 test("addClass(String)", function() {
-	expect(1);
+	expect(2);
 	var div = $("div");
 	div.addClass("test");
 	var pass = true;
@@ -934,10 +934,11 @@
 	 if ( div.get(i).className.indexOf("test") == -1 ) pass = false;
 	}
 	ok( pass, "Add Class" );
+	ok( !$('<span>test</span>\n<span>test</span>').addClass('test').eq(1).hasClass('test'), 'Test addClass with text nodes' );
 });
 
 test("removeClass(String) - simple", function() {
-	expect(3);
+	expect(4);
 	var div = $("div").addClass("test").removeClass("test"),
 		pass = true;
 	for ( var i = 0; i < div.size(); i++ ) {
@@ -957,7 +958,7 @@
 	reset();
 	var div = $("div:eq(0)").addClass("test").removeClass("");
 	ok( div.is('.test'), "Empty string passed to removeClass" );
-	
+	ok( !$('<span>test</span>\n<span>test</span>').addClass('test').removeClass('test').eq(1).hasClass('test'), 'Test removeClass with text nodes' );
 });
 
 test("toggleClass(String)", function() {
Index: src/core.js
===================================================================
--- src/core.js	(revision 3483)
+++ src/core.js	(working copy)
@@ -687,23 +687,24 @@
 		// internal only, use addClass("class")
 		add: function( elem, classNames ) {
 			jQuery.each((classNames || "").split(/\s+/), function(i, className){
-				if ( !jQuery.className.has( elem.className, className ) )
+				if ( elem && elem.nodeType == 1 && !jQuery.className.has( elem.className, className ) )
 					elem.className += (elem.className ? " " : "") + className;
 			});
 		},
 
 		// internal only, use removeClass("class")
 		remove: function( elem, classNames ) {
-			elem.className = classNames != undefined ?
-				jQuery.grep(elem.className.split(/\s+/), function(className){
-					return !jQuery.className.has( classNames, className );	
-				}).join(" ") :
-				"";
+			if ( elem && elem.nodeType == 1 )
+				elem.className = classNames != undefined ?
+					jQuery.grep(elem.className.split(/\s+/), function(className){
+						return !jQuery.className.has( classNames, className );	
+					}).join(" ") :
+					"";
 		},
 
 		// internal only, use is(".class")
 		has: function( elem, className ) {
-			return jQuery.inArray( className, (elem.className || elem).toString().split(/\s+/) ) > -1;
+			return elem && jQuery.inArray( className, (elem.className || elem).toString().split(/\s+/) ) > -1;
 		}
 	},