diff --git a/internal/uidriver/mobile/ui.go b/internal/uidriver/mobile/ui.go
index ea59d25eb..24c8baf27 100644
--- a/internal/uidriver/mobile/ui.go
+++ b/internal/uidriver/mobile/ui.go
@@ -18,9 +18,7 @@ package mobile
 
 import (
 	"context"
-	"errors"
 	"image"
-	"runtime"
 	"sync"
 	"time"
 
@@ -56,21 +54,7 @@ func Get() *UserInterface {
 	return theUI
 }
 
-func (u *UserInterface) Render(chError <-chan error) error {
-	runtime.LockOSThread()
-	defer runtime.UnlockOSThread()
-
-	if chError == nil {
-		return errors.New("ui: chError must not be nil")
-	}
-	// TODO: Check this is called on the rendering thread
-
-	select {
-	case err := <-chError:
-		return err
-	default:
-	}
-
+func (u *UserInterface) Render() {
 	renderCh <- struct{}{}
 	ctx, cancel := context.WithCancel(context.Background())
 	go func() {
@@ -78,7 +62,6 @@ func (u *UserInterface) Render(chError <-chan error) error {
 		cancel()
 	}()
 	opengl.Get().DoWork(ctx)
-	return nil
 }
 
 type UserInterface struct {
diff --git a/mobile/impl_mobile.go b/mobile/impl_mobile.go
index 3db4de31d..8cfb7cd3c 100644
--- a/mobile/impl_mobile.go
+++ b/mobile/impl_mobile.go
@@ -18,6 +18,7 @@ package mobile
 
 import (
 	"errors"
+	"runtime"
 
 	"github.com/hajimehoshi/ebiten"
 	"github.com/hajimehoshi/ebiten/internal/uidriver/mobile"
@@ -29,13 +30,24 @@ var (
 )
 
 func update() error {
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
 	if chError == nil {
 		return errors.New("mobile: chError must not be nil: Start is not called yet?")
 	}
 	if !running {
 		return errors.New("mobile: start must be called ahead of update")
 	}
-	return mobile.Get().Render(chError)
+
+	select {
+	case err := <-chError:
+		return err
+	default:
+	}
+
+	mobile.Get().Render()
+	return nil
 }
 
 func start(f func(*ebiten.Image) error, width, height int, scale float64, title string) {
diff --git a/mobile/mobile.go b/mobile/mobile.go
index 854201c69..8d25d9a0c 100644
--- a/mobile/mobile.go
+++ b/mobile/mobile.go
@@ -63,6 +63,7 @@ func Start(f func(*ebiten.Image) error, width, height int, scale float64, title
 //
 // Update returns error when 1) OpenGL error happens, or 2) f in Start returns error samely as ebiten.Run.
 func Update() error {
+	// TODO: Is it safe to call Lock before locking the OS thread?
 	mobileMutex.Lock()
 	defer mobileMutex.Unlock()