diff --git a/tools/build/feature/test-sched_getcpu.c b/tools/build/feature/test-sched_getcpu.c
index c4a148dd71048a0fb89eb24ea4527976702110c2..9c6b4cbffb1cae2759a524b70d36cee1b8f9f02e 100644
--- a/tools/build/feature/test-sched_getcpu.c
+++ b/tools/build/feature/test-sched_getcpu.c
@@ -1,4 +1,6 @@
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 #include <sched.h>
 
 int main(void)