diff --git a/ext/openssl/ossl_x509ext.c b/ext/openssl/ossl_x509ext.c
index ac46fcf15..a6eb81525 100644
--- a/ext/openssl/ossl_x509ext.c
+++ b/ext/openssl/ossl_x509ext.c
@@ -209,15 +209,16 @@ ossl_x509extfactory_create_ext(int argc, VALUE *argv, VALUE self)
     int nid;
     VALUE rconf;
     CONF *conf;
+    const char *oid_cstr = NULL;
 
     rb_scan_args(argc, argv, "21", &oid, &value, &critical);
-    StringValueCStr(oid);
     StringValue(value);
     if(NIL_P(critical)) critical = Qfalse;
 
-    nid = OBJ_ln2nid(RSTRING_PTR(oid));
-    if(!nid) nid = OBJ_sn2nid(RSTRING_PTR(oid));
-    if(!nid) ossl_raise(eX509ExtError, "unknown OID `%"PRIsVALUE"'", oid);
+    oid_cstr = StringValueCStr(oid);
+    nid = OBJ_ln2nid(oid_cstr);
+    if (nid != NID_undef)
+      oid_cstr = OBJ_nid2sn(nid);
 
     valstr = rb_str_new2(RTEST(critical) ? "critical," : "");
     rb_str_append(valstr, value);
@@ -228,7 +229,8 @@ ossl_x509extfactory_create_ext(int argc, VALUE *argv, VALUE self)
     rconf = rb_iv_get(self, "@config");
     conf = NIL_P(rconf) ? NULL : GetConfig(rconf);
     X509V3_set_nconf(ctx, conf);
-    ext = X509V3_EXT_nconf_nid(conf, ctx, nid, RSTRING_PTR(valstr));
+
+    ext = X509V3_EXT_nconf(conf, ctx, oid_cstr, RSTRING_PTR(valstr));
     X509V3_set_ctx_nodb(ctx);
     if (!ext){
 	ossl_raise(eX509ExtError, "%"PRIsVALUE" = %"PRIsVALUE, oid, valstr);
diff --git a/test/openssl/test_x509ext.rb b/test/openssl/test_x509ext.rb
index c04c06574..838780d32 100644
--- a/test/openssl/test_x509ext.rb
+++ b/test/openssl/test_x509ext.rb
@@ -78,6 +78,17 @@ def test_factory_create_extension_sn_ln
     assert_equal(@basic_constraints.to_der, bc_ln.to_der)
   end
 
+  def test_factory_create_extension_oid
+    ef = OpenSSL::X509::ExtensionFactory.new
+    ef.config = OpenSSL::Config.parse(<<~_end_of_cnf_)
+      [basic_constraints]
+      cA = BOOLEAN:TRUE
+      pathLenConstraint = INTEGER:2
+    _end_of_cnf_
+    bc_oid = ef.create_extension("2.5.29.19", "ASN1:SEQUENCE:basic_constraints", true)
+    assert_equal(@basic_constraints.to_der, bc_oid.to_der)
+  end
+
   def test_dup
     ext = OpenSSL::X509::Extension.new(@basic_constraints.to_der)
     assert_equal(@basic_constraints.to_der, ext.to_der)