--- /dev/null
+#!/bin/sh
+
+test_description='test handling of bogus index entries'
+. ./test-lib.sh
+
+test_expect_success 'create tree with null sha1' '
+ tree=$(printf "160000 commit $_z40\\tbroken\\n" | git mktree)
+'
+
+test_expect_success 'read-tree refuses to read null sha1' '
+ test_must_fail git read-tree $tree
+'
+
+test_expect_success 'GIT_ALLOW_NULL_SHA1 overrides refusal' '
+ GIT_ALLOW_NULL_SHA1=1 git read-tree $tree
+'
+
+test_expect_success 'git write-tree refuses to write null sha1' '
+ test_must_fail git write-tree
+'
+
+test_done