diff --git a/ext/objspace/objspace_dump.c b/ext/objspace/objspace_dump.c
index 50dead5773..bcee5312fc 100644
--- a/ext/objspace/objspace_dump.c
+++ b/ext/objspace/objspace_dump.c
@@ -436,9 +436,8 @@ dump_object(VALUE obj, struct dump_config *dc)
           case imemo_callinfo:
             mid = vm_ci_mid((const struct rb_callinfo *)obj);
             if (mid != 0) {
-                dump_append(dc, ", \"mid\":\"");
-                dump_append(dc, rb_id2name(mid));
-                dump_append(dc, "\"");
+                dump_append(dc, ", \"mid\":");
+                dump_append_string_value(dc, rb_id2str(mid));
             }
             break;