diff --git a/simgear/CMakeLists.txt b/simgear/CMakeLists.txt
index 6080b59e..e3ff31ef 100644
--- a/simgear/CMakeLists.txt
+++ b/simgear/CMakeLists.txt
@@ -5,7 +5,6 @@ foreach( mylibfolder
         bucket
         debug
         ephemeris
-        hla
         io
         magvar
         math
@@ -24,14 +23,18 @@ foreach( mylibfolder
 
 endforeach( mylibfolder )
 
-if (NOT SIMGEAR_HEADLESS)
+if(NOT SIMGEAR_HEADLESS)
     add_subdirectory(environment)
     add_subdirectory(screen)
     add_subdirectory(scene)
     add_subdirectory(sound)
-endif()
+endif(NOT SIMGEAR_HEADLESS)
 
 
+if(ENABLE_RTI)
+    add_subdirectory(hla)
+endif(ENABLE_RTI)
+
 
 set(HEADERS compiler.h constants.h sg_inlines.h ${PROJECT_BINARY_DIR}/simgear/version.h)
 install (FILES ${HEADERS}  DESTINATION include/simgear/)