Index: bin/stamps
===================================================================
--- bin/stamps	(revision 28)
+++ bin/stamps	(revision 29)
@@ -26,4 +26,12 @@
     s = Stamper()
     s.load_stamps()
+
+    # Set proper arguments if they have passed a date-based filter without
+    # a customer
+    if args.customer not in s.customers and not args.filter:
+        args.filter = args.customer
+        args.customer = None
+
+    # Call the proper methods, based on the given parameters
     if args.timeline:
         s.timeline()