diff --git a/compareRels.py b/compareRels.py
index bef6838..279f47a 100644
--- a/compareRels.py
+++ b/compareRels.py
@@ -59,7 +59,10 @@ def cmp_rel (url):
     v = get (url)
   except Exception as e:
     sys.stderr.write ("Could not get:" + url + ". Exception:" + str(e) + "\n")
-  print (url+';'+str(v['ahead_by'])+';'+str(v['behind_by']))
+  if 'ahead_by' in v and 'behind_by' in v:
+    print (url+';'+str(v['ahead_by'])+';'+str(v['behind_by']))
+  else:
+    sys.stderr.write ("Could not compare releases for: " + url + "; There exists no common ancestor between the two versions." + "\n")
 
 
 p2r = {}