diff --git a/ConfigureChecks.cmake b/ConfigureChecks.cmake
index bbbed63..efe0cc6 100644
--- a/ConfigureChecks.cmake
+++ b/ConfigureChecks.cmake
@@ -35,7 +35,7 @@ find_package( X11 )
 
 if( NOT X11_FOUND )
     tde_message_fatal( "X11 is required, but was not found on your system." )
-elseif( NOT X11_XExt_FOUND AND ( BUILD_KXVPLAYER OR BUILD_KXINEPLAYER ) )
+elseif( NOT X11_Xext_FOUND AND ( BUILD_KXVPLAYER OR BUILD_KXINEPLAYER ) )
     tde_message_fatal( "libXext is required, but was not found on your system." )
 elseif( NOT X11_Xv_FOUND AND BUILD_KXVPLAYER )
     tde_message_fatal( "libXv is required, but was not found on your system." )