diff --git a/scripts/maint/checkIncludes.py b/scripts/maint/checkIncludes.py
index b96b7f4b34b8e3b6b33faec877d29f9d81159e89..3c611675e406f7c7bbc6cac3a537c51df6f06ffe 100755
--- a/scripts/maint/checkIncludes.py
+++ b/scripts/maint/checkIncludes.py
@@ -1,4 +1,5 @@
 #!/usr/bin/python3
+# Copyright 2018 The Tor Project, Inc.  See LICENSE file for licensing info.
 
 import fnmatch
 import os
@@ -68,3 +69,4 @@ if trouble:
     err(
 """To change which includes are allowed in a C file, edit the {} files in its
 enclosing directory.""".format(RULES_FNAME))
+    sys.exit(1)