diff --git a/m4/ax_pthread.m4 b/m4/ax_pthread.m4
index e9787ce65..82ae1faf2 100644
--- a/m4/ax_pthread.m4
+++ b/m4/ax_pthread.m4
@@ -159,7 +159,7 @@ case ${host_os} in
         ax_pthread_flags="-pthreads pthread -mt -pthread $ax_pthread_flags"
         ;;
 
-        darwin12*)
+        darwin12* | darwin11.4*)
         ax_pthread_flags="$ax_pthread_flags"
         ;;