diff --git a/simulator/Makefile b/simulator/Makefile
index 3cdae45dad..43358a0de0 100644
--- a/simulator/Makefile
+++ b/simulator/Makefile
@@ -69,7 +69,7 @@ endif
 
 # C specific options here (added to USE_OPT).
 ifeq ($(USE_COPT),)
-  USE_COPT = -std=gnu99
+  USE_COPT = -std=gnu17
 endif
 
 # C++ specific options here (added to USE_OPT).