diff --git a/t/t1512-rev-parse-disambiguation.sh b/t/t1512-rev-parse-disambiguation.sh
index c19fb500cb..f06b045edd 100755
--- a/t/t1512-rev-parse-disambiguation.sh
+++ b/t/t1512-rev-parse-disambiguation.sh
@@ -282,7 +282,7 @@ test_expect_success 'rev-parse --disambiguate' '
 	# commits created by commit-tree in earlier tests share a
 	# different prefix.
 	git rev-parse --disambiguate=000000000 >actual &&
-	test $(wc -l <actual) = 16 &&
+	test_line_count = 16 actual &&
 	test "$(sed -e "s/^\(.........\).*/\1/" actual | sort -u)" = 000000000
 '