diff --git a/cronwrapper/__init__.py b/cronwrapper/__init__.py
index 254d1a0..629c3d8 100755
--- a/cronwrapper/__init__.py
+++ b/cronwrapper/__init__.py
@@ -216,7 +216,7 @@ def main():
     # Failure
     if previous_runs:
         # Not the first failure...
-        oldest = datetime.datetime.fromtimestamp(min(previous_runs.values()))
+        oldest = min(previous_runs.values())
         delta = datetime.timedelta(seconds=args.warn_interval)
         diff = now-oldest
         if diff > delta: