diff --git a/cmd/usb_mass_storage.c b/cmd/usb_mass_storage.c
index 86398fc..cb5260b 100644
--- a/cmd/usb_mass_storage.c
+++ b/cmd/usb_mass_storage.c
@@ -44,7 +44,7 @@ static void ums_fini(void)
 	for (i = 0; i < ums_count; i++)
 		free((void *)ums[i].name);
 	free(ums);
-	ums = 0;
+	ums = NULL;
 	ums_count = 0;
 }