diff --git a/src/gc.c b/src/gc.c
index a7537a015..23d22765c 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -502,6 +502,12 @@ obj_free(mrb_state *mrb, struct RBasic *obj)
     mrb_free(mrb, ((struct RRange*)obj)->edges);
     break;
 
+#ifdef ENABLE_STRUCT
+  case MRB_TT_STRUCT:
+    mrb_free(mrb, ((struct RStruct*)obj)->ptr);
+    break;
+#endif
+
   case MRB_TT_DATA:
     {
       struct RData *d = (struct RData*)obj;