diff --git a/Xcode/OpenSceneGraph/config/OpenThreads/Config b/Xcode/OpenSceneGraph/config/OpenThreads/Config
index 5c90a030d..38a7fea2f 100644
--- a/Xcode/OpenSceneGraph/config/OpenThreads/Config
+++ b/Xcode/OpenSceneGraph/config/OpenThreads/Config
@@ -2,9 +2,14 @@
 #define _OPENTHREADS_CONFIG
 
 #include <AvailabilityMacros.h>
+
+#define _OPENTHREADS_ATOMIC_USE_MUTEX
+
 #if defined(MAC_OS_X_VERSION_10_5)
     #if MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5
         #define _OPENTHREADS_ATOMIC_USE_BSD_ATOMIC
+	#undef _OPENTHREADS_ATOMIC_USE_MUTEX
+    #elif
     #endif
 #endif
 /* #undef _OPENTHREADS_ATOMIC_USE_GCC_BUILTINS */