diff --git a/src/if_mzsch.c b/src/if_mzsch.c
index a0c6483..d255d4a 100644
--- a/src/if_mzsch.c
+++ b/src/if_mzsch.c
@@ -1073,7 +1073,7 @@
 }
 
     static Scheme_Object *
-load_base_module_on_error(void *data)
+load_base_module_on_error(void *data UNUSED)
 {
     load_base_module_failed = TRUE;
     return scheme_null;