diff --git a/Doc/library/ssl.rst b/Doc/library/ssl.rst
index e2d3c3f..0498c11 100644
--- a/Doc/library/ssl.rst
+++ b/Doc/library/ssl.rst
@@ -366,7 +366,7 @@ Certificate handling
 
      >>> import ssl
      >>> ssl.cert_time_to_seconds("May  9 00:00:00 2007 GMT")
-     1178694000.0
+     1178668800 
      >>> import time
      >>> time.ctime(ssl.cert_time_to_seconds("May  9 00:00:00 2007 GMT"))
      'Wed May  9 00:00:00 2007'
diff --git a/Lib/ssl.py b/Lib/ssl.py
index 052a118..f81ef91 100644
--- a/Lib/ssl.py
+++ b/Lib/ssl.py
@@ -852,7 +852,8 @@ def cert_time_to_seconds(cert_time):
     a Python time value in seconds past the epoch."""
 
     import time
-    return time.mktime(time.strptime(cert_time, "%b %d %H:%M:%S %Y GMT"))
+    import calendar 
+    return calendar.timegm(time.strptime(cert_time, "%b %d %H:%M:%S %Y GMT"))
 
 PEM_HEADER = "-----BEGIN CERTIFICATE-----"
 PEM_FOOTER = "-----END CERTIFICATE-----"
diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py
index 6eb88d7..0352722 100644
--- a/Lib/test/test_ssl.py
+++ b/Lib/test/test_ssl.py
@@ -960,6 +960,10 @@ class ContextTests(unittest.TestCase):
         self.assertEqual(ctx.cert_store_stats(),
             {'x509_ca': 1, 'crl': 0, 'x509': 2})
 
+    def test_cert_time_to_seconds(self):
+        tsec = ssl.cert_time_to_seconds("May  9 00:00:00 2007 GMT")
+        self.assertEqual(tsec, 1178668800)
+
     def test_get_ca_certs(self):
         ctx = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
         self.assertEqual(ctx.get_ca_certs(), [])