diff --git a/tests/test_index.c b/tests/test_index.c
index ef43e6e3..673186c5 100644
--- a/tests/test_index.c
+++ b/tests/test_index.c
@@ -1625,6 +1625,9 @@ test_lzma_index_buffer_encode(void)
 	assert_lzma_ret(lzma_index_buffer_encode(idx, buffer, &out_pos,
 			0), LZMA_PROG_ERROR);
 	out_pos = 0;
+	assert_lzma_ret(lzma_index_buffer_encode(idx, buffer, &out_pos,
+			0), LZMA_BUF_ERROR);
+	assert_uint_eq(out_pos, 0);
 	assert_lzma_ret(lzma_index_buffer_encode(idx, buffer, &out_pos,
 			1), LZMA_BUF_ERROR);