Index: pyopenssl-0.13/OpenSSL/crypto/x509.c
===================================================================
--- pyopenssl-0.13.orig/OpenSSL/crypto/x509.c	2013-07-21 02:08:34.000000000 +0100
+++ pyopenssl-0.13/OpenSSL/crypto/x509.c	2013-07-21 02:08:57.529925025 +0100
@@ -340,16 +340,18 @@
 		return NULL;
 
 	if (ASN1_GENERALIZEDTIME_set_string(timestamp, when) == 0) {
-		ASN1_GENERALIZEDTIME dummy;
-		dummy.type = V_ASN1_GENERALIZEDTIME;
-		dummy.length = strlen(when);
-		dummy.data = (unsigned char *)when;
-		if (!ASN1_GENERALIZEDTIME_check(&dummy)) {
-			PyErr_SetString(PyExc_ValueError, "Invalid string");
-		} else {
-			PyErr_SetString(PyExc_RuntimeError, "Unknown ASN1_GENERALIZEDTIME_set_string failure");
+		if (ASN1_UTCTIME_set_string(timestamp, when) == 0) {
+			ASN1_GENERALIZEDTIME dummy;
+			dummy.type = V_ASN1_GENERALIZEDTIME;
+			dummy.length = strlen(when);
+			dummy.data = (unsigned char *)when;
+			if (!ASN1_GENERALIZEDTIME_check(&dummy)) {
+				PyErr_SetString(PyExc_ValueError, "Invalid string");
+			} else {
+				PyErr_SetString(PyExc_RuntimeError, "Unknown ASN1_GENERALIZEDTIME_set_string failure");
+			}
+			return NULL;
 		}
-		return NULL;
 	}
 	Py_INCREF(Py_None);
 	return Py_None;