diff --git a/routers/web/repo/wiki_test.go b/routers/web/repo/wiki_test.go
index 719cca304923f..4426529094659 100644
--- a/routers/web/repo/wiki_test.go
+++ b/routers/web/repo/wiki_test.go
@@ -9,6 +9,7 @@ import (
 	"net/url"
 	"testing"
 
+	"code.gitea.io/gitea/models/db"
 	repo_model "code.gitea.io/gitea/models/repo"
 	"code.gitea.io/gitea/models/unittest"
 	"code.gitea.io/gitea/modules/git"
@@ -221,3 +222,31 @@ func TestWikiRaw(t *testing.T) {
 		}
 	}
 }
+
+func TestDefaultWikiBranch(t *testing.T) {
+	unittest.PrepareTestEnv(t)
+
+	ctx, _ := contexttest.MockContext(t, "user2/repo1/wiki")
+	ctx.SetParams("*", "Home")
+	contexttest.LoadRepo(t, ctx, 1)
+	// by default the test fixture doesn't have "default wiki branch"
+	assert.Equal(t, "", ctx.Repo.Repository.DefaultWikiBranch)
+	Wiki(ctx) // after the visiting, the out-of-sync database record will update the branch name to "master"
+	repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 1})
+	assert.Equal(t, "master", ctx.Repo.Repository.DefaultWikiBranch)
+
+	// invalid branch name should fail
+	assert.Error(t, wiki_service.ChangeDefaultWikiBranch(db.DefaultContext, repo, "the bad name"))
+	repo = unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 1})
+	assert.Equal(t, "master", repo.DefaultWikiBranch)
+
+	// the same branch name, should succeed (actually a no-op)
+	assert.NoError(t, wiki_service.ChangeDefaultWikiBranch(db.DefaultContext, repo, "master"))
+	repo = unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 1})
+	assert.Equal(t, "master", repo.DefaultWikiBranch)
+
+	// change to another name
+	assert.NoError(t, wiki_service.ChangeDefaultWikiBranch(db.DefaultContext, repo, "main"))
+	repo = unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 1})
+	assert.Equal(t, "main", repo.DefaultWikiBranch)
+}
diff --git a/services/repository/migrate.go b/services/repository/migrate.go
index 17de922d1a725..aae2ddc1200ea 100644
--- a/services/repository/migrate.go
+++ b/services/repository/migrate.go
@@ -67,7 +67,7 @@ func cloneWiki(ctx context.Context, u *user_model.User, opts migration.MigrateOp
 	defaultBranch, err := wikiRepo.GetDefaultBranch()
 	if err != nil {
 		cleanIncompleteWikiPath()
-		return "", fmt.Errorf("failed to get wiki repo defaul branch for %q, err: %w", wikiPath, err)
+		return "", fmt.Errorf("failed to get wiki repo default branch for %q, err: %w", wikiPath, err)
 	}
 
 	return defaultBranch, nil
diff --git a/services/wiki/wiki.go b/services/wiki/wiki.go
index 628364e5fc1df..43da153e7dae7 100644
--- a/services/wiki/wiki.go
+++ b/services/wiki/wiki.go
@@ -20,6 +20,7 @@ import (
 	"code.gitea.io/gitea/modules/gitrepo"
 	"code.gitea.io/gitea/modules/log"
 	repo_module "code.gitea.io/gitea/modules/repository"
+	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/sync"
 	"code.gitea.io/gitea/modules/util"
 	asymkey_service "code.gitea.io/gitea/services/asymkey"
@@ -38,11 +39,15 @@ func InitWiki(ctx context.Context, repo *repo_model.Repository) error {
 		return nil
 	}
 
+	defaultBranchName := repo.DefaultWikiBranch
+	if defaultBranchName == "" { // usually this shouldn't happen, but for testing and for legacy data, it's safe to do the fallback
+		defaultBranchName = setting.Repository.DefaultBranch
+	}
 	if err := git.InitRepository(ctx, repo.WikiPath(), true, repo.ObjectFormatName); err != nil {
 		return fmt.Errorf("InitRepository: %w", err)
 	} else if err = repo_module.CreateDelegateHooks(repo.WikiPath()); err != nil {
 		return fmt.Errorf("createDelegateHooks: %w", err)
-	} else if _, _, err = git.NewCommand(ctx, "symbolic-ref", "HEAD").AddDynamicArguments(git.BranchPrefix + repo.DefaultWikiBranch).RunStdString(&git.RunOpts{Dir: repo.WikiPath()}); err != nil {
+	} else if _, _, err = git.NewCommand(ctx, "symbolic-ref", "HEAD").AddDynamicArguments(git.BranchPrefix + defaultBranchName).RunStdString(&git.RunOpts{Dir: repo.WikiPath()}); err != nil {
 		return fmt.Errorf("unable to set default wiki branch to master: %w", err)
 	}
 	return nil