diff --git a/t/t5560-http-backend-noserver.sh b/t/t5560-http-backend-noserver.sh
index eb6f910e7a..406432e7a5 100755
--- a/t/t5560-http-backend-noserver.sh
+++ b/t/t5560-http-backend-noserver.sh
@@ -5,6 +5,8 @@ test_description='test git-http-backend-noserver'
 
 HTTPD_DOCUMENT_ROOT_PATH="$TRASH_DIRECTORY"
 
+test_have_prereq MINGW && export GREP_OPTIONS=-U
+
 run_backend() {
 	echo "$2" |
 	QUERY_STRING="${1#*\?}" \