diff --git a/code/server/launcher/src/Main.cpp b/code/server/launcher/src/Main.cpp
index 8e27eb413d..e9d167d2c8 100644
--- a/code/server/launcher/src/Main.cpp
+++ b/code/server/launcher/src/Main.cpp
@@ -10,7 +10,9 @@
 #include "Server.h"
 
 #ifndef _WIN32
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 #include <pthread.h>
 #endif