diff --git a/tools/testing/selftests/clone3/Makefile b/tools/testing/selftests/clone3/Makefile
index ef7564cb7abe..79b19a2863a0 100644
--- a/tools/testing/selftests/clone3/Makefile
+++ b/tools/testing/selftests/clone3/Makefile
@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
-CFLAGS += -g -I../../../../usr/include/
+CFLAGS += -g -std=gnu99 -I../../../../usr/include/
 LDLIBS += -lcap
 
 TEST_GEN_PROGS := clone3 clone3_clear_sighand clone3_set_tid \