diff --git a/cronwrapper/__init__.py b/cronwrapper/__init__.py
index 999dcd9..44a5b82 100755
--- a/cronwrapper/__init__.py
+++ b/cronwrapper/__init__.py
@@ -40,7 +40,7 @@ def parse_args():
             help='Warn to stderr (as in "send mail") at most once within this time interval (seconds)',
             type=int,
             metavar='warn_interval',
-            default=[86400])
+            default=86400)
 
     parser.add_argument(
             '-L', '--no-lock',
@@ -184,7 +184,7 @@ def main():
             r.write("\nFalse\n")
             res = False
 
-    previous_runs = []
+    previous_runs = {}
     for root, dirs, files in os.walk(os.path.join(args.cachedir[0], args.name[0])):
         previous_runs = {
                 os.path.join(root, d): datetime.datetime.strptime(d, time_format) 
@@ -217,9 +217,9 @@ def main():
     if previous_runs:
         # Not the first failure...
         oldest = min(previous_runs.values())
-        if now-oldest > datetime.timedelta(seconds=args.warn_interval[0]):
+        if now-oldest > datetime.timedelta(seconds=args.warn_interval):
             # we have failed for a long time, send a report
-            print("Cronjob is still failing after {} seconds ({} failures)\n".format(args.warn_interval[0], len(previous_runs)))
+            print("Cronjob is still failing after {} seconds ({} failures)\n".format(args.warn_interval, len(previous_runs)))
             print_runs(previous_runs.keys())
         else:
             # Within limits, save the output for a later instance