1 files changed, 6 insertions, 0 deletions
diff --git a/commit.h b/commit.h
index dc4bf97d9f..23a3f364ed 100644
--- a/commit.h
+++ b/commit.h
@@ -22,6 +22,12 @@ struct commit {
 	unsigned int index;
 	timestamp_t date;
 	struct commit_list *parents;
+
+	/*
+	 * If the commit is loaded from the commit-graph file, then this
+	 * member may be NULL. Only access it through get_commit_tree()
+	 * or get_commit_tree_oid().
+	 */
 	struct tree *maybe_tree;
 	uint32_t graph_pos;
 };