diff --git a/templates/hooks--pre-commit.sample b/templates/hooks--pre-commit.sample
index e144712c85..29ed5ee486 100755
--- a/templates/hooks--pre-commit.sample
+++ b/templates/hooks--pre-commit.sample
@@ -28,7 +28,7 @@ if [ "$allownonascii" != "true" ] &&
 	# Note that the use of brackets around a tr range is ok here, (it's
 	# even required, for portability to Solaris 10's /usr/bin/tr), since
 	# the square bracket bytes happen to fall in the designated range.
-	test $(git diff --cached --name-only --diff-filter=A -z $against |
+	test $(git diff-index --cached --name-only --diff-filter=A -z $against |
 	  LC_ALL=C tr -d '[ -~]\0' | wc -c) != 0
 then
 	cat <<\EOF