--- kdelibs-4.0.4/khtml/css/html4.css	(Revision 813565)
+++ kdelibs-4.0.4/khtml/css/html4.css	(Revision 813566)
@@ -5,6 +5,8 @@
  * Konqueror/khtml relies on the existence of this style sheet for
  * rendering. Do not remove or modify this file unless you know
  * what you are doing.
+ *
+ * KHTML_STYLE_VERSION: 1
  */
 
 @namespace "http://www.w3.org/1999/xhtml";
--- kdelibs-4.0.4/khtml/css/cssstyleselector.cpp	(Revision 813565)
+++ kdelibs-4.0.4/khtml/css/cssstyleselector.cpp	(Revision 813566)
@@ -62,12 +62,16 @@
 #include <kconfig.h>
 #include <QtCore/QFile>
 #include <QtCore/QString>
+#include <QtCore/QFileInfo>
 
 #include <kdebug.h>
 #include <kurl.h>
 #include <assert.h>
 #include <stdlib.h>
 
+// keep in sync with html4.css'
+#define KHTML_STYLE_VERSION 1
+
 #undef RELATIVE
 #undef ABSOLUTE
 
@@ -386,6 +390,14 @@
 	    file[readbytes] = '\0';
 
 	QString style = QLatin1String( file.data() );
+	
+	QRegExp checkVersion( "KHTML_STYLE_VERSION:\\s*(\\d+)" );
+	checkVersion.setMinimal( true );
+	if (checkVersion.indexIn( style ) == -1 || checkVersion.cap(1).toInt() != KHTML_STYLE_VERSION) {
+	    qFatal( "!!!!!!! ERROR !!!!!!! - KHTML default stylesheet version mismatch. Aborting. Check your installation. File used was: %s. Expected STYLE_VERSION %d\n", 
+	        QFileInfo( f ).absoluteFilePath().toLatin1().data(), KHTML_STYLE_VERSION );
+        }
+	
 	if(s)
 	    style += s->settingsToCSS();
 	DOMString str(style);