diff --git a/code/CMakeModules/PCHSupport.cmake b/code/CMakeModules/PCHSupport.cmake
index aa7468cb6..020fa98d3 100644
--- a/code/CMakeModules/PCHSupport.cmake
+++ b/code/CMakeModules/PCHSupport.cmake
@@ -176,10 +176,21 @@ MACRO(PCH_SET_COMPILE_FLAGS _target)
   ENDIF()
 
   IF(CMAKE_VERSION VERSION_LESS "3.3.0")
-    GET_DIRECTORY_PROPERTY(_directory_flags DEFINITIONS)
-    GET_DIRECTORY_PROPERTY(_directory_definitions DIRECTORY ${CMAKE_SOURCE_DIR} DEFINITIONS)
-    LIST(APPEND _FLAGS ${_directory_flags})
-    LIST(APPEND _FLAGS ${_directory_definitions})
+    GET_DIRECTORY_PROPERTY(_DIRECTORY_FLAGS DEFINITIONS)
+
+    IF(_DIRECTORY_FLAGS)
+      FOREACH(item ${_DIRECTORY_FLAGS})
+        LIST(APPEND _FLAGS "$<$<BOOL:${item}>:-D$<JOIN:${item},-D>>")
+      ENDFOREACH()
+    ENDIF()
+    
+    GET_DIRECTORY_PROPERTY(_DIRECTORY_DEFINITIONS DIRECTORY ${CMAKE_SOURCE_DIR} DEFINITIONS)
+
+    IF(_DIRECTORY_DEFINITIONS)
+      FOREACH(item ${_DIRECTORY_DEFINITIONS})
+        LIST(APPEND _FLAGS "$<$<BOOL:${item}>:-D$<JOIN:${item},-D>>")
+      ENDFOREACH()
+    ENDIF()
   ENDIF()
 
   # Format definitions