Index: src/libs/tgfclient/CMakeLists.txt
--- src/libs/tgfclient/CMakeLists.txt.orig
+++ src/libs/tgfclient/CMakeLists.txt
@@ -82,6 +82,7 @@ ENDIF(WIN32)
 
 IF(UNIX AND NOT HAIKU)
     ADD_X11_LIBRARY(tgfclient)
+    INCLUDE_DIRECTORIES(${X11_INCLUDE_DIR})
     IF(OPTION_XRANDR)
         ADD_XRANDR_LIBRARY(tgfclient)
     ENDIF(OPTION_XRANDR)
