diff --git a/winpr/libwinpr/synch/CMakeLists.txt b/winpr/libwinpr/synch/CMakeLists.txt
index cd93e84f8..fbc607292 100644
--- a/winpr/libwinpr/synch/CMakeLists.txt
+++ b/winpr/libwinpr/synch/CMakeLists.txt
@@ -18,6 +18,15 @@
 set(MODULE_NAME "winpr-synch")
 set(MODULE_PREFIX "WINPR_SYNCH")
 
+INCLUDE (CheckLibraryExists) 
+list(APPEND CMAKE_REQUIRED_DEFINITIONS -D_GNU_SOURCE)
+check_library_exists(pthread pthread_tryjoin_np "" HAVE_PTHREAD_GNU_EXT)
+list(REMOVE_ITEM CMAKE_REQUIRED_DEFINITIONS -D_GNU_SOURCE)
+
+if(HAVE_PTHREAD_GNU_EXT)
+	add_definitions(-D_GNU_SOURCE -DHAVE_PTHREAD_GNU_EXT)
+endif(HAVE_PTHREAD_GNU_EXT)
+	
 include_directories(../thread)
 
 set(${MODULE_PREFIX}_SRCS
diff --git a/winpr/libwinpr/synch/wait.c b/winpr/libwinpr/synch/wait.c
index dccb071ae..9a8eba120 100644
--- a/winpr/libwinpr/synch/wait.c
+++ b/winpr/libwinpr/synch/wait.c
@@ -77,7 +77,7 @@ DWORD WaitForSingleObject(HANDLE hHandle, DWORD dwMilliseconds)
 		{
 			if (dwMilliseconds != INFINITE)
 			{
-#if _GNU_SOURCE
+#if HAVE_PTHREAD_GNU_EXT
 				struct timespec timeout;
 
 				clock_gettime(CLOCK_REALTIME, &timeout);
@@ -105,7 +105,7 @@ DWORD WaitForSingleObject(HANDLE hHandle, DWORD dwMilliseconds)
 
 		mutex = (WINPR_MUTEX*) Object;
 
-#if _GNU_SOURCE
+#if HAVE_PTHREAD_GNU_EXT
 		if (dwMilliseconds != INFINITE)
 		{
 			struct timespec timeout;