diff --git a/graphicscontext.go b/graphicscontext.go
index f3e6584b9..e6ab20716 100644
--- a/graphicscontext.go
+++ b/graphicscontext.go
@@ -164,9 +164,7 @@ func (c *graphicsContext) UpdateAndDraw(context *opengl.Context, updateCount int
 		return err
 	}
 	for i := 0; i < updateCount; i++ {
-		if err := theImagesForRestoring.clearVolatileImages(); err != nil {
-			return err
-		}
+		theImagesForRestoring.clearVolatileImages()
 		setRunningSlowly(i < updateCount-1)
 		if err := c.f(c.offscreen); err != nil {
 			return err
diff --git a/image.go b/image.go
index 30d2e61aa..9f0a0ed9c 100644
--- a/image.go
+++ b/image.go
@@ -121,13 +121,12 @@ func (i *images) restore(context *opengl.Context) error {
 	return nil
 }
 
-func (i *images) clearVolatileImages() error {
+func (i *images) clearVolatileImages() {
 	i.m.Lock()
 	defer i.m.Unlock()
 	for img := range i.images {
 		img.clearIfVolatile()
 	}
-	return nil
 }
 
 // Image represents an image.
@@ -187,10 +186,17 @@ func (i *Image) Fill(clr color.Color) error {
 // Even if the argument image is mutated after this call,
 // the drawing result is never affected.
 //
+// When the image is disposed, DrawImage does nothing.
+//
+// When image is as same as i, DrawImage panics.
+//
+// DrawImage always returns nil as of 1.5.0-alpha.
+//
 // This function is concurrent-safe.
 func (i *Image) DrawImage(image *Image, options *DrawImageOptions) error {
 	theImagesForRestoring.resetPixelsIfDependingOn(i, glContext())
-	return i.impl.DrawImage(image, options)
+	i.impl.DrawImage(image, options)
+	return nil
 }
 
 // Bounds returns the bounds of the image.
diff --git a/imageimpl.go b/imageimpl.go
index ebc9640a4..517526001 100644
--- a/imageimpl.go
+++ b/imageimpl.go
@@ -84,7 +84,7 @@ func (i *imageImpl) clearIfVolatile() {
 	i.restorable.ClearIfVolatile()
 }
 
-func (i *imageImpl) DrawImage(image *Image, options *DrawImageOptions) error {
+func (i *imageImpl) DrawImage(image *Image, options *DrawImageOptions) {
 	// Calculate vertices before locking because the user can do anything in
 	// options.ImageParts interface without deadlock (e.g. Call Image functions).
 	if options == nil {
@@ -104,19 +104,18 @@ func (i *imageImpl) DrawImage(image *Image, options *DrawImageOptions) error {
 	w, h := image.impl.restorable.Size()
 	vs := vertices(parts, w, h, &options.GeoM.impl)
 	if len(vs) == 0 {
-		return nil
+		return
 	}
 	if i == image.impl {
-		return errors.New("ebiten: Image.DrawImage: image should be different from the receiver")
+		panic("ebiten: Image.DrawImage: image must be different from the receiver")
 	}
 	i.m.Lock()
 	defer i.m.Unlock()
 	if i.restorable == nil {
-		return errors.New("ebiten: image is already disposed")
+		return
 	}
 	mode := opengl.CompositeMode(options.CompositeMode)
 	i.restorable.DrawImage(image.impl.restorable, vs, options.ColorM.impl, mode)
-	return nil
 }
 
 func (i *imageImpl) At(x, y int, context *opengl.Context) color.Color {