diff --git a/internal/uidriver/mobile/ui.go b/internal/uidriver/mobile/ui.go
index d1fb06c94..6a6c81c93 100644
--- a/internal/uidriver/mobile/ui.go
+++ b/internal/uidriver/mobile/ui.go
@@ -58,6 +58,7 @@ func Get() *UserInterface {
 	return theUI
 }
 
+// Update is called from mobile/ebitenmobileview.
 func (u *UserInterface) Update() {
 	u.m.Lock()
 	fg := u.foreground
@@ -332,6 +333,7 @@ func (u *UserInterface) ScreenSizeInFullscreen() (int, int) {
 	return 0, 0
 }
 
+// SetScreenSizeAndScale is called from mobile/ebitenmobileview.
 func (u *UserInterface) SetScreenSizeAndScale(width, height int, scale float64) {
 	// Called from ebitenmobileview.
 	u.m.Lock()
diff --git a/mobile/ebitenmobileview/funcs.go b/mobile/ebitenmobileview/funcs.go
index d1d9efb19..27fd402ab 100644
--- a/mobile/ebitenmobileview/funcs.go
+++ b/mobile/ebitenmobileview/funcs.go
@@ -47,6 +47,7 @@ func layout(viewWidth, viewHeight int, viewRectSetter ViewRectSetter) {
 		return
 	}
 
+	// TODO: Layout must be called every frame like uiContext already did.
 	w, h := theState.game.Layout(int(viewWidth), int(viewHeight))
 	scaleX := float64(viewWidth) / float64(w)
 	scaleY := float64(viewHeight) / float64(h)