diff --git a/common.py b/common.py
index 3a3a866..da459e5 100644
--- a/common.py
+++ b/common.py
@@ -8,6 +8,7 @@ import urlparse
 import sys
 
 # Check that we have a recent enough version
+# Older versions don't provide the 'json' attribute on responses.
 assert(requests.__version__ > '0.12')
 
 class HumbugAPI():