diff --git a/commit-graph.c b/commit-graph.c
index 196e817a84..7807d94562 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -277,7 +277,7 @@ struct commit_graph *parse_commit_graph(void *graph_map, int fd,
 	last_chunk_id = 0;
 	last_chunk_offset = 8;
 	chunk_lookup = data + 8;
-	for (i = 0; i < graph->num_chunks; i++) {
+	for (i = 0; i <= graph->num_chunks; i++) {
 		uint32_t chunk_id;
 		uint64_t chunk_offset;
 		int chunk_repeated = 0;
diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index 18304a65e4..79e7fbcd40 100755
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -488,7 +488,7 @@ test_expect_success 'detect bad hash version' '
 '
 
 test_expect_success 'detect low chunk count' '
-	corrupt_graph_and_verify $GRAPH_BYTE_CHUNK_COUNT "\02" \
+	corrupt_graph_and_verify $GRAPH_BYTE_CHUNK_COUNT "\01" \
 		"missing the .* chunk"
 '