diff --git a/t/t5510-fetch.sh b/t/t5510-fetch.sh
index 603277655b..6aa63b1e74 100755
--- a/t/t5510-fetch.sh
+++ b/t/t5510-fetch.sh
@@ -688,7 +688,7 @@ test_expect_success 'fetching with auto-gc does not lock up' '
 	)
 '
 
-test_expect_success 'fetch aligned output' '
+test_expect_success C_LOCALE_OUTPUT 'fetch aligned output' '
 	git clone . full-output &&
 	test_commit looooooooooooong-tag &&
 	(
@@ -703,7 +703,7 @@ test_expect_success 'fetch aligned output' '
 	test_cmp expect actual
 '
 
-test_expect_success 'fetch compact output' '
+test_expect_success C_LOCALE_OUTPUT 'fetch compact output' '
 	git clone . compact &&
 	test_commit extraaa &&
 	(