diff --git a/CMakeLists.txt b/CMakeLists.txt
index 33bb252..acd2a80 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -188,5 +188,5 @@ ExternalProject_Add(FlightGear
     UPDATE_COMMAND ""      # or update.
     SOURCE_DIR ${CMAKE_CURRENT_LIST_DIR}/flightgear
     BINARY_DIR fgbuild 
-    CMAKE_ARGS ${FG_CMAKE_ARGS} -DCMAKE_INSTALL_PREFIX=${FG_INSTALL_PREFIX} -DCMAKE_PREFIX_PATH="${OSG_INSTALL_PREFIX};${SG_INSTALL_PREFIX}"
+    CMAKE_ARGS ${FG_CMAKE_ARGS} -DCMAKE_INSTALL_PREFIX=${FG_INSTALL_PREFIX} -DCMAKE_PREFIX_PATH=${OSG_INSTALL_PREFIX} -DSIMGEAR_DIR=${SG_INSTALL_PREFIX}
 )