diff --git a/src/openssl.hxx b/src/openssl.hxx
index 6f00f80..15faa1d 100644
--- a/src/openssl.hxx
+++ b/src/openssl.hxx
@@ -205,7 +205,7 @@ namespace openssl {
         if (!len) throw x509_copy_failed();
         const unsigned char* d2(d);
         _x509 = d2i_X509(0, &d2, len);
-        free(d);
+        OPENSSL_free(d);
         if (!_x509) throw x509_copy_failed();
       }
       //! Take over OpenSSL allocated certificate.
@@ -226,6 +226,14 @@ namespace openssl {
         _x509 = d2i_X509(0, &d2, len);
         if (!_x509) throw x509_copy_failed();
       }
+      //! Get DER encoded subject.
+      std::string subjectDER() const {
+        char* c(0);
+        int len(i2d_X509_NAME(X509_get_subject_name(_x509), &c));
+        std::String res(c, len);
+        OPENSSL_free(c);
+        return res;
+      }
     private:
       ::X509* _x509;
   };