diff --git a/setup.py b/setup.py
index 67cefdc48..4ee56576b 100644
--- a/setup.py
+++ b/setup.py
@@ -39,7 +39,7 @@ install_requires = [
     'ConfigArgParse>=0.9.3',
     'configobj',
     'cryptography>=0.7',  # load_pem_x509_certificate
-    'parsedatetime',
+    'parsedatetime>=1.3',  # Calendar.parseDT
     'psutil>=2.1.0',  # net_connections introduced in 2.1.0
     'PyOpenSSL',
     'pyrfc3339',