diff --git a/builtin/fsck.c b/builtin/fsck.c
index c11cb2a95f..1b032eebb1 100644
--- a/builtin/fsck.c
+++ b/builtin/fsck.c
@@ -731,19 +731,19 @@ static int fsck_head_link(const char *head_ref_name,
 	return 0;
 }
 
-static int fsck_cache_tree(struct cache_tree *it)
+static int fsck_cache_tree(struct cache_tree *it, const char *index_path)
 {
 	int i;
 	int err = 0;
 
 	if (verbose)
-		fprintf_ln(stderr, _("Checking cache tree"));
+		fprintf_ln(stderr, _("Checking cache tree of %s"), index_path);
 
 	if (0 <= it->entry_count) {
 		struct object *obj = parse_object(the_repository, &it->oid);
 		if (!obj) {
-			error(_("%s: invalid sha1 pointer in cache-tree"),
-			      oid_to_hex(&it->oid));
+			error(_("%s: invalid sha1 pointer in cache-tree of %s"),
+			      oid_to_hex(&it->oid), index_path);
 			errors_found |= ERROR_REFS;
 			return 1;
 		}
@@ -754,11 +754,12 @@ static int fsck_cache_tree(struct cache_tree *it)
 			err |= objerror(obj, _("non-tree in cache-tree"));
 	}
 	for (i = 0; i < it->subtree_nr; i++)
-		err |= fsck_cache_tree(it->down[i]->cache_tree);
+		err |= fsck_cache_tree(it->down[i]->cache_tree, index_path);
 	return err;
 }
 
-static int fsck_resolve_undo(struct index_state *istate)
+static int fsck_resolve_undo(struct index_state *istate,
+			     const char *index_path)
 {
 	struct string_list_item *item;
 	struct string_list *resolve_undo = istate->resolve_undo;
@@ -781,8 +782,9 @@ static int fsck_resolve_undo(struct index_state *istate)
 
 			obj = parse_object(the_repository, &ru->oid[i]);
 			if (!obj) {
-				error(_("%s: invalid sha1 pointer in resolve-undo"),
-				      oid_to_hex(&ru->oid[i]));
+				error(_("%s: invalid sha1 pointer in resolve-undo of %s"),
+				      oid_to_hex(&ru->oid[i]),
+				      index_path);
 				errors_found |= ERROR_REFS;
 				continue;
 			}
@@ -795,7 +797,8 @@ static int fsck_resolve_undo(struct index_state *istate)
 	return 0;
 }
 
-static void fsck_index(struct index_state *istate)
+static void fsck_index(struct index_state *istate, const char *index_path,
+		       int is_main_index)
 {
 	unsigned int i;
 
@@ -816,12 +819,14 @@ static void fsck_index(struct index_state *istate)
 		obj = &blob->object;
 		obj->flags |= USED;
 		fsck_put_object_name(&fsck_walk_options, &obj->oid,
-				     ":%s", istate->cache[i]->name);
+				     "%s:%s",
+				     is_main_index ? "" : index_path,
+				     istate->cache[i]->name);
 		mark_object_reachable(obj);
 	}
 	if (istate->cache_tree)
-		fsck_cache_tree(istate->cache_tree);
-	fsck_resolve_undo(istate);
+		fsck_cache_tree(istate->cache_tree, index_path);
+	fsck_resolve_undo(istate, index_path);
 }
 
 static void mark_object_for_connectivity(const struct object_id *oid)
@@ -994,12 +999,19 @@ int cmd_fsck(int argc, const char **argv, const char *prefix)
 			struct worktree *wt = *p;
 			struct index_state istate =
 				INDEX_STATE_INIT(the_repository);
+			char *path;
 
-			if (read_index_from(&istate,
-					    worktree_git_path(wt, "index"),
+			/*
+			 * Make a copy since the buffer is reusable
+			 * and may get overwritten by other calls
+			 * while we're examining the index.
+			 */
+			path = xstrdup(worktree_git_path(wt, "index"));
+			if (read_index_from(&istate, path,
 					    get_worktree_git_dir(wt)) > 0)
-				fsck_index(&istate);
+				fsck_index(&istate, path, wt->is_current);
 			discard_index(&istate);
+			free(path);
 		}
 		free_worktrees(worktrees);
 	}
diff --git a/t/t1450-fsck.sh b/t/t1450-fsck.sh
index e01a519a69..82c92de7ca 100755
--- a/t/t1450-fsck.sh
+++ b/t/t1450-fsck.sh
@@ -1032,7 +1032,25 @@ test_expect_success 'fsck detects problems in worktree index' '
 	blob=$(git -C wt rev-parse :file) &&
 	remove_object $blob &&
 
-	test_must_fail git fsck
+	test_must_fail git fsck --name-objects >actual 2>&1 &&
+	cat >expect <<-EOF &&
+	missing blob $blob (.git/worktrees/wt/index:file)
+	EOF
+	test_cmp expect actual
+'
+
+test_expect_success 'fsck reports problems in main index without filename' '
+	test_when_finished "rm -f .git/index && git read-tree HEAD" &&
+	echo "this object will be removed to break the main index" >file &&
+	git add file &&
+	blob=$(git rev-parse :file) &&
+	remove_object $blob &&
+
+	test_must_fail git fsck --name-objects >actual 2>&1 &&
+	cat >expect <<-EOF &&
+	missing blob $blob (:file)
+	EOF
+	test_cmp expect actual
 '
 
 test_done