diff --git a/configs/common/Simulation.py b/configs/common/Simulation.py
index e7fb878..a8d3771 100644
--- a/configs/common/Simulation.py
+++ b/configs/common/Simulation.py
@@ -196,7 +196,7 @@
             if match:
                 cpts.append(match.group(1))
 
-        cpts.sort(lambda a,b: cmp(long(a), long(b)))
+        cpts.sort(key = lambda a: long(a))
 
         cpt_num = options.checkpoint_restore
         if cpt_num > len(cpts):