diff --git a/Modules/CheckIPOSupported/foo.c b/Modules/CheckIPOSupported/foo.c
index 1e5659789e..6a64a998ac 100644
--- a/Modules/CheckIPOSupported/foo.c
+++ b/Modules/CheckIPOSupported/foo.c
@@ -1,4 +1,4 @@
-int foo()
+int foo(void)
 {
   return 0x42;
 }
diff --git a/Modules/CheckIPOSupported/main.c b/Modules/CheckIPOSupported/main.c
index 8d2ab01cb9..db0956cbe3 100644
--- a/Modules/CheckIPOSupported/main.c
+++ b/Modules/CheckIPOSupported/main.c
@@ -1,4 +1,4 @@
-int foo();
+int foo(void);
 
 int main(void)
 {