diff --git a/src/bindings/fluid_rtkit.c b/src/bindings/fluid_rtkit.c
index 55be61498..38fac13f5 100644
--- a/src/bindings/fluid_rtkit.c
+++ b/src/bindings/fluid_rtkit.c
@@ -25,6 +25,11 @@
   SOFTWARE.
 ***/
 
+#ifndef _GNU_SOURCE
+// required for syscall()
+#define _GNU_SOURCE
+#endif
+
 #include "fluid_sys.h"
 
 #ifdef DBUS_SUPPORT
@@ -34,11 +39,6 @@
 
 #if defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__) || defined(__DragonFly__)
 
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE
-
-#endif
-
 #include <sys/syscall.h>
 #include <sys/resource.h>