diff --git a/ext/openssl/ossl_asn1.c b/ext/openssl/ossl_asn1.c
index e00c664c54..0085d4beab 100644
--- a/ext/openssl/ossl_asn1.c
+++ b/ext/openssl/ossl_asn1.c
@@ -1823,8 +1823,8 @@ do{\
     rb_define_method(cASN1EndOfContent, "initialize", ossl_asn1eoc_initialize, 0);
     rb_define_method(cASN1EndOfContent, "to_der", ossl_asn1eoc_to_der, 0);
 
-    rb_global_variable(&class_tag_map);
     class_tag_map = rb_hash_new();
+    rb_gc_register_mark_object(class_tag_map);
     rb_hash_aset(class_tag_map, cASN1EndOfContent, INT2NUM(V_ASN1_EOC));
     rb_hash_aset(class_tag_map, cASN1Boolean, INT2NUM(V_ASN1_BOOLEAN));
     rb_hash_aset(class_tag_map, cASN1Integer, INT2NUM(V_ASN1_INTEGER));