Index: /CKEditor/trunk/CHANGES.html
===================================================================
--- /CKEditor/trunk/CHANGES.html	(revision 6096)
+++ /CKEditor/trunk/CHANGES.html	(revision 6097)
@@ -122,4 +122,5 @@
 		<li><a href="http://dev.ckeditor.com/ticket/5850">#5850</a> : [IE] Inline style misbehaviors at the beginning of numbered/bulleted list.</li>
 		<li><a href="http://dev.ckeditor.com/ticket/6580">#6580</a> : [IE9] Flash dialog doesn't get filled up.</li>
+		<li><a href="http://dev.ckeditor.com/ticket/6447">#6447</a> : Outdent list with "indentClasses" config doesn't work.</li>
 		<li>Updated the following language files:<ul>
 			<li><a href="http://dev.ckeditor.com/ticket/6427">#6427</a> : Ukrainian;</li>
Index: /CKEditor/trunk/_source/plugins/indent/plugin.js
===================================================================
--- /CKEditor/trunk/_source/plugins/indent/plugin.js	(revision 6096)
+++ /CKEditor/trunk/_source/plugins/indent/plugin.js	(revision 6097)
@@ -1,3 +1,3 @@
-/*
+/*
 Copyright (c) 2003-2010, CKSource - Frederico Knabben. All rights reserved.
 For licensing, see LICENSE.html or http://ckeditor.com/license
@@ -248,8 +248,6 @@
 					indentStep = Math.min( indentStep, editor.config.indentClasses.length );
 					indentStep = Math.max( indentStep, 0 );
-					var className = CKEDITOR.tools.ltrim( element.$.className.replace( self.classNameRegex, '' ) );
-					if ( indentStep < 1 )
-						element.$.className = className;
-					else
+					element.$.className = CKEDITOR.tools.ltrim( element.$.className.replace( self.classNameRegex, '' ) );
+					if ( indentStep > 0 )
 						element.addClass( editor.config.indentClasses[ indentStep - 1 ] );
 				}