X509 with embedded X509, ruby problem patch

diff --git a/ext/openssl/ossl_x509cert.c b/ext/openssl/ossl_x509cert.c
index 80a0b76..0e602d1 100644
--- a/ext/openssl/ossl_x509cert.c
+++ b/ext/openssl/ossl_x509cert.c
@@ -136,21 +136,35 @@ ossl_x509_initialize(int argc, VALUE *argv, VALUE self)
 {
     BIO *in;
     X509 *x509, *x = DATA_PTR(self);
-    VALUE arg;
+    VALUE arg, argtype;
+    int filetype = 0; // 0 not given, 1 PEM, 2 DER

-    if (rb_scan_args(argc, argv, "01", &arg) == 0) {
+    rb_scan_args(argc, argv, "02", &arg, &argtype);
+
+    if (NIL_P(arg)) {
        /* create just empty X509Cert */
        return self;
     }
+
+    if (TYPE(argtype) == T_STRING) {
+        if (strcmp(StringValueCStr(argtype), "PEM") == 0) filetype = 1;
+        if (strcmp(StringValueCStr(argtype), "DER") == 0) filetype = 2;
+    }
+
     arg = ossl_to_der_if_possible(arg);
     in = ossl_obj2bio(arg);
-    x509 = PEM_read_bio_X509(in, &x, NULL, NULL);
-    DATA_PTR(self) = x;
-    if (!x509) {
-       OSSL_BIO_reset(in);
-       x509 = d2i_X509_bio(in, &x);
-       DATA_PTR(self) = x;
+
+    if (NIL_P(argtype) || filetype == 1) {
+        x509 = PEM_read_bio_X509(in, &x, NULL, NULL);
+        DATA_PTR(self) = x;
+    } else if (NIL_P(argtype) || filetype == 2) {
+        if (!x509) {
+           OSSL_BIO_reset(in);
+           x509 = d2i_X509_bio(in, &x);
+           DATA_PTR(self) = x;
+        }
     }
+