diff --git a/src/makefile.am b/src/makefile.am
index 151fb91..9027d5c 100644
--- a/src/makefile.am
+++ b/src/makefile.am
@@ -32,6 +32,10 @@ libcryptoki___la_LIBADD += -lpcsclite
 endif
 endif
 
+noinst_PROGRAMS = versiontest
+versiontest_SOURCES = versiontest.cxx
+
+
 clean-local:
 	-rm -r ${QMAKE_TARGET}.app
 
diff --git a/src/openssl.hxx b/src/openssl.hxx
index fc9d8e3..af45769 100644
--- a/src/openssl.hxx
+++ b/src/openssl.hxx
@@ -23,9 +23,13 @@
 #elif OPENSSL_VERSION_NUMBER < 0x10000000L
 #  define OPENSSL_0
 #  define V0_CONST const
+#  define CV_STACK
+#  define CV_X509
 #else
 #  define OPENSSL_1
-#  define V0_CONST /* no const in openssl 1.0.0 */
+#  define V0_CONST const
+#  define CV_STACK (_STACK*)
+#  define CV_X509 (STACK_OF(X509)*)
 #endif
 
 #include <openssl/x509v3.h> // BASIC_CONSTRAINTS
@@ -1071,8 +1075,8 @@ namespace openssl {
             throw pkcs12_parsing_failed(filename);
           if (pkey) _key = new PrivateKey(pkey);
           if (cert) _cert = new X509(cert);
-          for (int i(sk_num(ca)); i>0; --i)
-            _ca.push_back(new X509((::X509*)sk_pop(ca)));
+          for (int i(sk_num(CV_STACK ca)); i>0; --i)
+            _ca.push_back(new X509((::X509*)sk_pop(CV_STACK ca)));
           PKCS12_free(p12);
         } catch (...) {
           PKCS12_free(p12);
@@ -1160,8 +1164,8 @@ namespace openssl {
         BIO_free(mem);
         if (!p7) throw pkcs7_parsing_failed();
         try {
-          if (PKCS7_type_is_signed(p7)) while (p7->d.sign->cert->num>0)
-            _certs.push_back(new X509((::X509*)sk_pop(p7->d.sign->cert)));
+          if (PKCS7_type_is_signed(p7)) while ((CV_STACK p7->d.sign->cert)->num>0)
+            _certs.push_back(new X509((::X509*)sk_pop(CV_STACK p7->d.sign->cert)));
           else //! @todo to be implemented: check for other types
             throw pkcs7_unsupported_format();
           PKCS7_free(p7);
diff --git a/src/versiontest.cxx b/src/versiontest.cxx
new file mode 100644
index 0000000..125c01e
--- /dev/null
+++ b/src/versiontest.cxx
@@ -0,0 +1,16 @@
+#include <openssl/opensslv.h> 
+#ifndef OPENSSL_VERSION_NUMBER 
+#  error OpenSSL Version Number not Found 
+#elif OPENSSL_VERSION_NUMBER < 0x10000000L 
+#  define NAME "an old pre 1.0.0 version of OpenSSL"
+#else 
+#  define NAME "a new 1.0.x version of OpenSSL"
+#endif 
+
+#include <iostream>
+#include <iomanip>
+
+int main() {
+  std::cout<<std::hex<<OPENSSL_VERSION_NUMBER<<" is "<<NAME<<std::endl;
+  return 0;
+}