Index: src/tools/trackgen/CMakeLists.txt
--- src/tools/trackgen/CMakeLists.txt.orig
+++ src/tools/trackgen/CMakeLists.txt
@@ -52,6 +52,7 @@ ENDIF(MINGW)
 
 IF(UNIX)
     SD_INSTALL_FILES(MAN man6 PREFIX ${SOURCE_DIR}/doc/man FILES ${_TARGET_NAME}.6)
+    INCLUDE_DIRECTORIES(${X11_INCLUDE_DIR})
 ENDIF(UNIX)
 
 SD_INSTALL_FILES(BIN TARGETS ${_TARGET_NAME})
