diff --git a/server-util/make-users.py b/server-util/make-users.py
index 0861f52..3852d40 100644
--- a/server-util/make-users.py
+++ b/server-util/make-users.py
@@ -54,10 +54,12 @@ def main():
         mailbox = args.email.split('@')[0]
     except IndexError:
         print("ERROR: This doesn't look like an email address: \"{}\"".format(args.email))
+        sys.exit(1)
     try:
         emailDomain = args.email.split('@')[1]
     except IndexError:
         print("ERROR: This doesn't look like an email address: \"{}\"".format(args.email))
+        sys.exit(1)
 
     done = 0
     while( done < args.num ):