diff --git a/commit.c b/commit.c
index e3e7352e69..fd8723502e 100644
--- a/commit.c
+++ b/commit.c
@@ -434,6 +434,27 @@ static inline void set_commit_tree(struct commit *c, struct tree *t)
 	c->maybe_tree = t;
 }
 
+static void load_tree_from_commit_contents(struct repository *r, struct commit *commit)
+{
+	enum object_type type;
+	unsigned long size;
+	char *buf;
+	const char *p;
+	struct object_id tree_oid;
+
+	buf = odb_read_object(r->objects, &commit->object.oid, &type, &size);
+	if (!buf)
+		return;
+
+	if (type == OBJ_COMMIT &&
+	    skip_prefix(buf, "tree ", &p) &&
+	    !parse_oid_hex_algop(p, &tree_oid, &p, r->hash_algo) &&
+	    *p == '\n')
+		set_commit_tree(commit, lookup_tree(r, &tree_oid));
+
+	free(buf);
+}
+
 struct tree *repo_get_commit_tree(struct repository *r,
 				  const struct commit *commit)
 {
@@ -443,7 +464,17 @@ struct tree *repo_get_commit_tree(struct repository *r,
 	if (commit_graph_position(commit) != COMMIT_NOT_FROM_GRAPH)
 		return get_commit_tree_in_graph(r, commit);
 
-	return NULL;
+	/*
+	 * This is either a corrupt commit, or one which we partially loaded
+	 * from a graph file but then subsequently threw away the graph data.
+	 *
+	 * Optimistically assume it's the latter and try to reload from
+	 * scratch. This gives a performance penalty if it really is a corrupt
+	 * commit, but presumably that happens rarely (and only once per
+	 * process).
+	 */
+	load_tree_from_commit_contents(r, (struct commit *)commit);
+	return commit->maybe_tree;
 }
 
 struct object_id *get_commit_tree_oid(const struct commit *commit)
diff --git a/t/t5604-clone-reference.sh b/t/t5604-clone-reference.sh
index 470bfb610c..c232ab8c15 100755
--- a/t/t5604-clone-reference.sh
+++ b/t/t5604-clone-reference.sh
@@ -360,4 +360,27 @@ test_expect_success SYMLINKS 'clone repo with symlinked objects directory' '
 	grep "is a symlink, refusing to clone with --local" err
 '
 
+test_expect_success 'dissociate from repo with commit graph' '
+	git init orig &&
+	# We are trying to make sure the dissociated repo can
+	# find the tree of the tip commit, so the test could still
+	# serve its purpose with an empty tree. But having actual
+	# content future-proofs us against any kind of internal
+	# empty-tree optimizations.
+	echo content >orig/file &&
+	git -C orig add . &&
+	git -C orig commit -m foo &&
+
+	# We will use graph.git as our "local" source to dissociate
+	# from.
+	git clone --bare orig graph.git &&
+	git -C graph.git commit-graph write --reachable &&
+
+	# And then finally clone orig, using graph.git to get our objects. This
+	# must be non-bare so that we perform the checkout step, which will
+	# need to access the tree of HEAD, which we will have originally loaded
+	# via the commit graph.
+	git clone --no-local --reference graph.git --dissociate orig clone
+'
+
 test_done