diff --git a/t/test-lib.sh b/t/test-lib.sh
index 3d46630e6e..7b4c531e60 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -1642,6 +1642,12 @@ case $uname_s in
 	test_set_prereq GREP_STRIPS_CR
 	test_set_prereq WINDOWS
 	GIT_TEST_CMP="GIT_DIR=/dev/null git diff --no-index --ignore-cr-at-eol --"
+	if ! type iconv >/dev/null 2>&1
+	then
+		iconv () {
+			test-tool iconv "$@"
+		}
+	fi
 	;;
 *CYGWIN*)
 	test_set_prereq POSIXPERM