diff --git a/crypto/stack/stack.c b/crypto/stack/stack.c
index 2eb531fd0d4f287e016af363ad45127d60c684ef..02857f044664bf4ee34c21a6514855f9ee1ec718 100644
--- a/crypto/stack/stack.c
+++ b/crypto/stack/stack.c
@@ -111,7 +111,7 @@ err:
 
 STACK *sk_new_null(void)
 	{
-	return sk_new((int (*)(const char * const *, const char * const *))NULL);
+	return sk_new((int (*)(const char * const *, const char * const *))0);
 	}
 
 STACK *sk_new(int (*c)(const char * const *, const char * const *))