diff --git a/Modules/FindGTK2.cmake b/Modules/FindGTK2.cmake
index a91da3312..fecf92924 100644
--- a/Modules/FindGTK2.cmake
+++ b/Modules/FindGTK2.cmake
@@ -267,6 +267,8 @@ function(_GTK2_FIND_INCLUDE_DIR _var _hdr)
             /usr/local/lib
             /usr/lib64
             /usr/lib
+            /usr/X11R6/include
+            /usr/X11R6/lib
             /opt/gnome/include
             /opt/gnome/lib
             /opt/openwin/include