diff --git a/test/cfg/posix.c b/test/cfg/posix.c
index eaab9683d63..18400eff3c2 100644
--- a/test/cfg/posix.c
+++ b/test/cfg/posix.c
@@ -1023,7 +1023,7 @@ void nullPointer(char *p, int fd, pthread_mutex_t mutex)
     pthread_mutex_unlock(NULL);
 }
 
-void* f_returns_NULL(void*)
+void* f_returns_NULL(void* arg)
 {
     return NULL;
 }