diff --git a/scripts/coccinelle/test-operator-cleanup b/scripts/coccinelle/test-operator-cleanup
index e7822542a4..28b4d4f588 100755
--- a/scripts/coccinelle/test-operator-cleanup
+++ b/scripts/coccinelle/test-operator-cleanup
@@ -1,4 +1,17 @@
 #!/usr/bin/perl -w -p -i
+#
+# Copyright (c) 2001 Matej Pfajfar.
+# Copyright (c) 2001-2004, Roger Dingledine.
+# Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+# Copyright (c) 2007-2019, The Tor Project, Inc.
+# See LICENSE for licensing information
+
+# This script looks for instances of C comparison operators as macro arguments,
+# and replaces them with our OP_* equivalents.
+#
+# Some macros that take operators are our tt_int_op() testing macro, and the
+# standard timercmp() macro.  Coccinelle can't handle their syntax, however,
+# unless we give them their operators as a macro too.
 
 next if m#^ */\*# or m#^ *\* #;