diff --git a/src/gc.c b/src/gc.c
index ddab7c87..121e1016 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -326,6 +326,9 @@ gc_mark_object(pic_state *pic, struct pic_object *obj)
     if (proc->env) {
       gc_mark_object(pic, (struct pic_object *)proc->env);
     }
+    if (! proc->cfunc_p) {
+      gc_mark_object(pic, (struct pic_object *)proc->u.irep);
+    }
     break;
   }
   case PIC_TT_PORT: {