diff --git a/ArchiveExtractor/Amenities.py b/ArchiveExtractor/Amenities.py
index 38a88482a9935b18731d8087714ffe3880610903..68fdeb7bcd9308b86e3b74be2fd3b2a1adf5018d 100644
--- a/ArchiveExtractor/Amenities.py
+++ b/ArchiveExtractor/Amenities.py
@@ -83,7 +83,7 @@ def _dateparse(datestr):
             raise Exception("Could not parse argument to a date") from e
 
         # Convert all in minutes
-        minutes = q*{'m':1, 'h':60, 'd':60*24, 'm':30*60*24}[datestr[-1]]
+        minutes = q*{'m':1, 'h':60, 'd':60*24, 'M':30*60*24}[datestr[-1]]
 
         return datetime.timedelta(minutes=minutes)