diff --git a/src/openssl.hxx b/src/openssl.hxx
index dc58680..c8d14d7 100644
--- a/src/openssl.hxx
+++ b/src/openssl.hxx
@@ -724,7 +724,7 @@ namespace openssl {
       //! Initialize from DER encoded cerificate.
       X509(const std::string& der): _x509(0) {
         OPENSSL_LOG("log");
-        const unsigned char* c((const unsigned char*)der.begin().operator->());
+        unsigned char* c((unsigned char*)der.begin().operator->());
         if (!(_x509=d2i_X509(0, &c, der.size())) ||
             (const char*)c!=der.begin().operator->()+der.size())
           throw x509_decoding_failed(der);
@@ -734,7 +734,7 @@ namespace openssl {
         unsigned char* d(0);
         int len(i2d_X509(o._x509, &d));
         if (!len) throw x509_copy_failed();
-        const unsigned char* d2(d);
+        unsigned char* d2(d);
         _x509 = d2i_X509(0, &d2, len);
         OPENSSL_free(d);
         if (!_x509) throw x509_copy_failed();
@@ -755,7 +755,7 @@ namespace openssl {
         unsigned char* d(0);
         int len(i2d_X509(o._x509, &d));
         if (!len) throw x509_copy_failed();
-        const unsigned char* d2(d);
+        unsigned char* d2(d);
         _x509 = d2i_X509(0, &d2, len);
         OPENSSL_free(d);
         if (!_x509) throw x509_copy_failed();