diff --git a/t/t3700-add.sh b/t/t3700-add.sh
index 37729ba258..62557e6a3d 100755
--- a/t/t3700-add.sh
+++ b/t/t3700-add.sh
@@ -91,6 +91,7 @@ test_expect_success 'error out when attempting to add ignored ones without -f' '
 '

 test_expect_success 'error out when attempting to add ignored ones but add others' '
+       export GIT_ICASE_PATHSPECS=1 &&
        touch a.if &&
        test_must_fail git add a.?? &&
        ! (git ls-files | grep "\\.ig") &&