diff --git a/extlib/benz/gc.c b/extlib/benz/gc.c
index 56d504a4..7a2a0e2b 100644
--- a/extlib/benz/gc.c
+++ b/extlib/benz/gc.c
@@ -442,7 +442,7 @@ gc_finalize_object(pic_state *pic, struct object *obj)
   }
 }
 
-#ifdef PIC_USE_BITMAPGC
+#if PIC_USE_BITMAPGC
 # include "./gc/bitmap.c"
 #else
 # include "./gc/markandsweep.c"
diff --git a/extlib/benz/include/picrin/private/object.h b/extlib/benz/include/picrin/private/object.h
index 3cd1f19b..20633abf 100644
--- a/extlib/benz/include/picrin/private/object.h
+++ b/extlib/benz/include/picrin/private/object.h
@@ -17,7 +17,7 @@ KHASH_DECLARE(env, struct identifier *, symbol *)
 KHASH_DECLARE(dict, symbol *, pic_value)
 KHASH_DECLARE(weak, struct object *, pic_value)
 
-#ifdef PIC_USE_BITMAPGC
+#if PIC_USE_BITMAPGC
 # define OBJECT_HEADER                           \
   unsigned char tt;
 #else