diff --git a/check-topic-merges b/check-topic-merges
index 1a3a96d471..b6d66b840d 100755
--- a/check-topic-merges
+++ b/check-topic-merges
@@ -1,13 +1,13 @@
 #!/bin/sh
+#
+# Run this script _after_ making a proposed merge into a copy of
+# the target branch (e.g. "master") to see if it contains unrelated
+# merging back from the upstream.
+#
 F=`git diff-tree -r --name-only HEAD^ HEAD`
 echo "The topic modifies these paths:"
 echo "$F" | sed -e 's/^/	/'
 
-# Documentation/git-cvsexportcommit.txt
-# git-cvsexportcommit.perl
-# git-cvsserver.perl
-B=`git merge-base master HEAD`
-# 45f75a0167b4a4693f2c6005bf7db231ca91ecc8 (master)
 _x40='[0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f]'
 _x40="$_x40$_x40$_x40$_x40$_x40$_x40$_x40$_x40"
 git rev-list --parents master..HEAD^2 |
@@ -15,7 +15,7 @@ sed -ne "/^$_x40 $_x40 $_x40/p" |
 while read merge first second
 do
 	echo
-	# first is the previous cvs topic tip, second is what was merged into
+	# First is the previous cvs topic tip, second is what was merged into
 	# it.  Does the merge have anything to do with adjust the topic to
 	# updated upstream?
 	git name-rev "$merge"
@@ -27,4 +27,3 @@ do
 		echo "$out" ;;
 	esac
 done
-