diff --git a/builtin/checkout.c b/builtin/checkout.c
index 55e3a89a85..505d3f7bf3 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -921,7 +921,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		}
 	}
 
-	if (!cache_tree_fully_valid(the_repository->index->cache_tree))
+	if (!cache_tree_fully_valid(the_repository->index))
 		cache_tree_update(the_repository->index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 
 	if (write_locked_index(the_repository->index, &lock_file, COMMIT_LOCK))
diff --git a/builtin/commit.c b/builtin/commit.c
index 28f6174503..840b6b4083 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -484,7 +484,7 @@ static const char *prepare_index(const char **argv, const char *prefix,
 				       LOCK_DIE_ON_ERROR);
 		refresh_cache_or_die(refresh_flags);
 		if (the_repository->index->cache_changed
-		    || !cache_tree_fully_valid(the_repository->index->cache_tree))
+		    || !cache_tree_fully_valid(the_repository->index))
 			cache_tree_update(the_repository->index, WRITE_TREE_SILENT);
 		if (write_locked_index(the_repository->index, &index_lock,
 				       COMMIT_LOCK | SKIP_IF_UNCHANGED))
diff --git a/cache-tree.c b/cache-tree.c
index a220372a42..6103b3fcb3 100644
--- a/cache-tree.c
+++ b/cache-tree.c
@@ -275,22 +275,29 @@ static void discard_unused_subtrees(struct cache_tree *it)
 	}
 }
 
-int cache_tree_fully_valid(struct cache_tree *it)
+static int cache_tree_fully_valid_recursive(struct object_database *odb,
+					    struct cache_tree *it)
 {
 	int i;
 	if (!it)
 		return 0;
 	if (it->entry_count < 0 ||
-	    !odb_has_object(the_repository->objects, &it->oid,
+	    !odb_has_object(odb, &it->oid,
 			    ODB_HAS_OBJECT_RECHECK_PACKED | ODB_HAS_OBJECT_FETCH_PROMISOR))
 		return 0;
 	for (i = 0; i < it->subtree_nr; i++) {
-		if (!cache_tree_fully_valid(it->down[i]->cache_tree))
+		if (!cache_tree_fully_valid_recursive(odb, it->down[i]->cache_tree))
 			return 0;
 	}
 	return 1;
 }
 
+int cache_tree_fully_valid(struct index_state *istate)
+{
+	return cache_tree_fully_valid_recursive(istate->repo->objects,
+						istate->cache_tree);
+}
+
 static int must_check_existence(const struct cache_entry *ce)
 {
 	return !(repo_has_promisor_remote(the_repository) && ce_skip_worktree(ce));
@@ -775,7 +782,7 @@ struct tree *write_in_core_index_as_tree(struct repository *repo,
 	int was_valid, ret;
 
 	was_valid = index_state->cache_tree &&
-		    cache_tree_fully_valid(index_state->cache_tree);
+		    cache_tree_fully_valid(index_state);
 
 	ret = write_index_as_tree_internal(&o, index_state, was_valid, 0, NULL);
 	if (ret == WRITE_TREE_UNMERGED_INDEX) {
@@ -811,7 +818,7 @@ int write_index_as_tree(struct object_id *oid, struct index_state *index_state,
 
 	was_valid = !(flags & WRITE_TREE_IGNORE_CACHE_TREE) &&
 		    index_state->cache_tree &&
-		    cache_tree_fully_valid(index_state->cache_tree);
+		    cache_tree_fully_valid(index_state);
 
 	ret = write_index_as_tree_internal(oid, index_state, was_valid, flags,
 					   prefix);
diff --git a/cache-tree.h b/cache-tree.h
index f8bddae523..4b3f60d6db 100644
--- a/cache-tree.h
+++ b/cache-tree.h
@@ -31,7 +31,7 @@ int cache_tree_subtree_pos(struct cache_tree *it, const char *path, int pathlen)
 void cache_tree_write(struct strbuf *, struct cache_tree *root);
 struct cache_tree *cache_tree_read(const char *buffer, unsigned long size);
 
-int cache_tree_fully_valid(struct cache_tree *);
+int cache_tree_fully_valid(struct index_state *);
 int cache_tree_update(struct index_state *, int);
 int cache_tree_verify(struct repository *, struct index_state *);
 
diff --git a/sequencer.c b/sequencer.c
index 65afd100d9..11a95c031b 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -814,7 +814,7 @@ static int do_recursive_merge(struct repository *r,
 
 static struct object_id *get_cache_tree_oid(struct index_state *istate)
 {
-	if (!cache_tree_fully_valid(istate->cache_tree))
+	if (!cache_tree_fully_valid(istate))
 		if (cache_tree_update(istate, 0)) {
 			error(_("unable to update cache tree"));
 			return NULL;
diff --git a/sparse-index.c b/sparse-index.c
index c1fa231a89..3d77dadae5 100644
--- a/sparse-index.c
+++ b/sparse-index.c
@@ -228,7 +228,7 @@ int convert_to_sparse(struct index_state *istate, int flags)
 	if (index_has_unmerged_entries(istate))
 		return 0;
 
-	if (!cache_tree_fully_valid(istate->cache_tree)) {
+	if (!cache_tree_fully_valid(istate)) {
 		/* Clear and recompute the cache-tree */
 		cache_tree_free(&istate->cache_tree);
 
diff --git a/unpack-trees.c b/unpack-trees.c
index 154d6d40a1..f6bb1e6d2b 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -2086,7 +2086,7 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
 			}
 
 			if (!o->skip_cache_tree_update &&
-			    !cache_tree_fully_valid(o->internal.result.cache_tree))
+			    !cache_tree_fully_valid(&o->internal.result))
 				cache_tree_update(&o->internal.result,
 						  WRITE_TREE_SILENT |
 						  WRITE_TREE_REPAIR);