diff --git a/modules/doctor/heads.go b/modules/doctor/heads.go
new file mode 100644
index 00000000000..ec14aa4eadb
--- /dev/null
+++ b/modules/doctor/heads.go
@@ -0,0 +1,91 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package doctor
+
+import (
+	"context"
+
+	repo_model "code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/log"
+)
+
+func synchronizeRepoHeads(ctx context.Context, logger log.Logger, autofix bool) error {
+	numRepos := 0
+	numHeadsBroken := 0
+	numDefaultBranchesBroken := 0
+	numReposUpdated := 0
+	err := iterateRepositories(ctx, func(repo *repo_model.Repository) error {
+		numRepos++
+		runOpts := &git.RunOpts{Dir: repo.RepoPath()}
+
+		_, _, defaultBranchErr := git.NewCommand(ctx, "rev-parse", "--", repo.DefaultBranch).RunStdString(runOpts)
+
+		head, _, headErr := git.NewCommand(ctx, "symbolic-ref", "--short", "HEAD").RunStdString(runOpts)
+
+		// what we expect: default branch is valid, and HEAD points to it
+		if headErr == nil && defaultBranchErr == nil && head == repo.DefaultBranch {
+			return nil
+		}
+
+		if headErr != nil {
+			numHeadsBroken++
+		}
+		if defaultBranchErr != nil {
+			numDefaultBranchesBroken++
+		}
+
+		// if default branch is broken, let the user fix that in the UI
+		if defaultBranchErr != nil {
+			logger.Warn("Default branch for %s/%s doesn't point to a valid commit", repo.OwnerName, repo.Name)
+			return nil
+		}
+
+		// if we're not autofixing, that's all we can do
+		if !autofix {
+			return nil
+		}
+
+		// otherwise, let's try fixing HEAD
+		err := git.NewCommand(ctx, "symbolic-ref", "--", "HEAD", repo.DefaultBranch).Run(runOpts)
+		if err != nil {
+			logger.Warn("Failed to fix HEAD for %s/%s: %v", repo.OwnerName, repo.Name, err)
+			return nil
+		}
+		numReposUpdated++
+		return nil
+	})
+	if err != nil {
+		logger.Critical("Error when fixing repo HEADs: %v", err)
+	}
+
+	if autofix {
+		logger.Info("Out of %d repos, HEADs for %d are now fixed and HEADS for %d are still broken", numRepos, numReposUpdated, numDefaultBranchesBroken+numHeadsBroken-numReposUpdated)
+	} else {
+		if numHeadsBroken == 0 && numDefaultBranchesBroken == 0 {
+			logger.Info("All %d repos have their HEADs in the correct state")
+		} else {
+			if numHeadsBroken == 0 && numDefaultBranchesBroken != 0 {
+				logger.Critical("Default branches are broken for %d/%d repos", numDefaultBranchesBroken, numRepos)
+			} else if numHeadsBroken != 0 && numDefaultBranchesBroken == 0 {
+				logger.Warn("HEADs are broken for %d/%d repos", numHeadsBroken, numRepos)
+			} else {
+				logger.Critical("Out of %d repos, HEADS are broken for %d and default branches are broken for %d", numRepos, numHeadsBroken, numDefaultBranchesBroken)
+			}
+		}
+	}
+
+	return err
+}
+
+func init() {
+	Register(&Check{
+		Title:     "Synchronize repo HEADs",
+		Name:      "synchronize-repo-heads",
+		IsDefault: true,
+		Run:       synchronizeRepoHeads,
+		Priority:  7,
+	})
+}