diff --git a/imagedumper_notmobile.go b/imagedumper_notmobile.go
index 25d57b5ec..2310b7771 100644
--- a/imagedumper_notmobile.go
+++ b/imagedumper_notmobile.go
@@ -18,64 +18,39 @@
 package ebiten
 
 import (
-	"errors"
 	"fmt"
 	"os"
-	"syscall"
 	"time"
 
 	"github.com/hajimehoshi/ebiten/v2/internal/debug"
 	"github.com/hajimehoshi/ebiten/v2/internal/ui"
 )
 
-// availableFilename returns a filename that is valid as a new file or directory.
-func availableFilename(prefix, postfix string) (string, error) {
+func datetimeForFilename() string {
 	const datetimeFormat = "20060102030405"
-
 	now := time.Now()
-	name := fmt.Sprintf("%s%s%s", prefix, now.Format(datetimeFormat), postfix)
-	for i := 1; ; i++ {
-		if _, err := os.Stat(name); err != nil {
-			if os.IsNotExist(err) || errors.Is(err, syscall.ENOSYS) {
-				break
-			}
-			if !os.IsNotExist(err) {
-				return "", err
-			}
-		}
-		name = fmt.Sprintf("%s%s_%d%s", prefix, now.Format(datetimeFormat), i, postfix)
-	}
-	return name, nil
+	return now.Format(datetimeFormat)
 }
 
 func takeScreenshot(screen *Image) error {
-	newname, err := availableFilename("screenshot_", ".png")
+	name := "screenshot_" + datetimeForFilename() + ".png"
+	blackbg := !IsScreenTransparent()
+	dumpedName, err := screen.image.DumpScreenshot(name, blackbg)
 	if err != nil {
 		return err
 	}
-
-	blackbg := !IsScreenTransparent()
-	if err := screen.image.DumpScreenshot(newname, blackbg); err != nil {
-		return err
-	}
-
-	if _, err := fmt.Fprintf(os.Stderr, "Saved screenshot: %s\n", newname); err != nil {
+	if _, err := fmt.Fprintf(os.Stderr, "Saved screenshot: %s\n", dumpedName); err != nil {
 		return err
 	}
 	return nil
 }
 
 func dumpInternalImages() error {
-	dir, err := availableFilename("internalimages_", "")
+	dumpedDir, err := ui.DumpImages("internalimages_" + datetimeForFilename())
 	if err != nil {
 		return err
 	}
-
-	if err := ui.DumpImages(dir); err != nil {
-		return err
-	}
-
-	if _, err := fmt.Fprintf(os.Stderr, "Dumped the internal images at: %s\n", dir); err != nil {
+	if _, err := fmt.Fprintf(os.Stderr, "Dumped the internal images at: %s\n", dumpedDir); err != nil {
 		return err
 	}
 	return nil
diff --git a/internal/atlas/image.go b/internal/atlas/image.go
index beccb29b9..e0f82f37f 100644
--- a/internal/atlas/image.go
+++ b/internal/atlas/image.go
@@ -733,7 +733,7 @@ func (i *Image) allocate(putOnAtlas bool) {
 	i.node = n
 }
 
-func (i *Image) DumpScreenshot(graphicsDriver graphicsdriver.Graphics, path string, blackbg bool) error {
+func (i *Image) DumpScreenshot(graphicsDriver graphicsdriver.Graphics, path string, blackbg bool) (string, error) {
 	backendsM.Lock()
 	defer backendsM.Unlock()
 
@@ -786,7 +786,7 @@ func BeginFrame(graphicsDriver graphicsdriver.Graphics) error {
 	return nil
 }
 
-func DumpImages(graphicsDriver graphicsdriver.Graphics, dir string) error {
+func DumpImages(graphicsDriver graphicsdriver.Graphics, dir string) (string, error) {
 	backendsM.Lock()
 	defer backendsM.Unlock()
 	return restorable.DumpImages(graphicsDriver, dir)
diff --git a/internal/buffered/image.go b/internal/buffered/image.go
index 0fbcb82c4..b7b8dcf7c 100644
--- a/internal/buffered/image.go
+++ b/internal/buffered/image.go
@@ -113,7 +113,7 @@ func (i *Image) ReadPixels(graphicsDriver graphicsdriver.Graphics, pixels []byte
 	return nil
 }
 
-func (i *Image) DumpScreenshot(graphicsDriver graphicsdriver.Graphics, name string, blackbg bool) error {
+func (i *Image) DumpScreenshot(graphicsDriver graphicsdriver.Graphics, name string, blackbg bool) (string, error) {
 	checkDelayedCommandsFlushed("Dump")
 	return i.img.DumpScreenshot(graphicsDriver, name, blackbg)
 }
diff --git a/internal/graphicscommand/image_js.go b/internal/graphicscommand/image_js.go
index 210e12357..b4f63ffac 100644
--- a/internal/graphicscommand/image_js.go
+++ b/internal/graphicscommand/image_js.go
@@ -39,26 +39,26 @@ func download(buf *bytes.Buffer, mime string, path string) {
 	a.Call("click")
 }
 
-func (i *Image) Dump(graphicsDriver graphicsdriver.Graphics, path string, blackbg bool, rect image.Rectangle) error {
+func (i *Image) Dump(graphicsDriver graphicsdriver.Graphics, path string, blackbg bool, rect image.Rectangle) (string, error) {
 	// Screen image cannot be dumped.
 	if i.screen {
-		return nil
+		return "", nil
 	}
 
 	buf := &bytes.Buffer{}
 	if err := i.dumpTo(buf, graphicsDriver, blackbg, rect); err != nil {
-		return err
+		return "", err
 	}
 
 	download(buf, "image/png", i.dumpName(path))
 
-	return nil
+	return path, nil
 }
 
 // DumpImages dumps all the specified images to the specified directory.
 //
 // This is for testing usage.
-func DumpImages(images []*Image, graphicsDriver graphicsdriver.Graphics, dir string) error {
+func DumpImages(images []*Image, graphicsDriver graphicsdriver.Graphics, dir string) (string, error) {
 	buf := &bytes.Buffer{}
 	zw := zip.NewWriter(buf)
 
@@ -70,17 +70,18 @@ func DumpImages(images []*Image, graphicsDriver graphicsdriver.Graphics, dir str
 
 		f, err := zw.Create(img.dumpName("*.png"))
 		if err != nil {
-			return err
+			return "", err
 		}
 
 		if err := img.dumpTo(f, graphicsDriver, false, image.Rect(0, 0, img.width, img.height)); err != nil {
-			return err
+			return "", err
 		}
 	}
 
 	zw.Close()
 
-	download(buf, "archive/zip", dir+".zip")
+	zip := dir + ".zip"
+	download(buf, "archive/zip", zip)
 
-	return nil
+	return zip, nil
 }
diff --git a/internal/graphicscommand/image_notjs.go b/internal/graphicscommand/image_notjs.go
index d805f418e..4ff2fda34 100644
--- a/internal/graphicscommand/image_notjs.go
+++ b/internal/graphicscommand/image_notjs.go
@@ -18,6 +18,8 @@
 package graphicscommand
 
 import (
+	"errors"
+	"fmt"
 	"image"
 	"os"
 	"path/filepath"
@@ -25,38 +27,74 @@ import (
 	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver"
 )
 
-func (i *Image) Dump(graphicsDriver graphicsdriver.Graphics, path string, blackbg bool, rect image.Rectangle) error {
-	// Screen image cannot be dumped.
-	if i.screen {
-		return nil
+func (i *Image) Dump(graphicsDriver graphicsdriver.Graphics, path string, blackbg bool, rect image.Rectangle) (string, error) {
+	p, err := availableFilename(path)
+	if err != nil {
+		return "", err
 	}
+	path = p
 
 	path = i.dumpName(path)
 	f, err := os.Create(path)
 	if err != nil {
-		return err
+		return "", err
 	}
 	defer f.Close()
 
 	if err := i.dumpTo(f, graphicsDriver, blackbg, rect); err != nil {
-		return err
+		return "", err
 	}
 
-	return nil
+	return path, nil
 }
 
 // DumpImages dumps all the current images to the specified directory.
 //
 // This is for testing usage.
-func DumpImages(images []*Image, graphicsDriver graphicsdriver.Graphics, dir string) error {
+func DumpImages(images []*Image, graphicsDriver graphicsdriver.Graphics, dir string) (string, error) {
+	d, err := availableFilename(dir)
+	if err != nil {
+		return "", err
+	}
+	dir = d
+
 	if err := os.Mkdir(dir, 0755); err != nil {
-		return err
+		return "", err
 	}
 
 	for _, img := range images {
-		if err := img.Dump(graphicsDriver, filepath.Join(dir, "*.png"), false, image.Rect(0, 0, img.width, img.height)); err != nil {
-			return err
+		// Screen image cannot be dumped.
+		if img.screen {
+			continue
+		}
+
+		f, err := os.Create(filepath.Join(dir, img.dumpName("*.png")))
+		if err != nil {
+			return "", err
+		}
+		defer f.Close()
+
+		if err := img.dumpTo(f, graphicsDriver, false, image.Rect(0, 0, img.width, img.height)); err != nil {
+			return "", err
 		}
 	}
-	return nil
+
+	return dir, nil
+}
+
+// availableFilename returns a filename that is valid as a new file or directory.
+func availableFilename(name string) (string, error) {
+	ext := filepath.Ext(name)
+	base := name[:len(name)-len(ext)]
+
+	for i := 1; ; i++ {
+		if _, err := os.Stat(name); err != nil {
+			if errors.Is(err, os.ErrNotExist) {
+				break
+			}
+			return "", err
+		}
+		name = fmt.Sprintf("%s_%d%s", base, i, ext)
+	}
+	return name, nil
 }
diff --git a/internal/mipmap/mipmap.go b/internal/mipmap/mipmap.go
index 45b7f9c0a..5dc581b8e 100644
--- a/internal/mipmap/mipmap.go
+++ b/internal/mipmap/mipmap.go
@@ -45,7 +45,7 @@ func New(width, height int, imageType atlas.ImageType) *Mipmap {
 	}
 }
 
-func (m *Mipmap) DumpScreenshot(graphicsDriver graphicsdriver.Graphics, name string, blackbg bool) error {
+func (m *Mipmap) DumpScreenshot(graphicsDriver graphicsdriver.Graphics, name string, blackbg bool) (string, error) {
 	return m.orig.DumpScreenshot(graphicsDriver, name, blackbg)
 }
 
diff --git a/internal/restorable/image.go b/internal/restorable/image.go
index e227c304b..572547638 100644
--- a/internal/restorable/image.go
+++ b/internal/restorable/image.go
@@ -668,7 +668,7 @@ func (i *Image) isInvalidated(graphicsDriver graphicsdriver.Graphics) (bool, err
 	return i.image.IsInvalidated(), nil
 }
 
-func (i *Image) Dump(graphicsDriver graphicsdriver.Graphics, path string, blackbg bool, rect image.Rectangle) error {
+func (i *Image) Dump(graphicsDriver graphicsdriver.Graphics, path string, blackbg bool, rect image.Rectangle) (string, error) {
 	return i.image.Dump(graphicsDriver, path, blackbg, rect)
 }
 
diff --git a/internal/restorable/images.go b/internal/restorable/images.go
index d9f424903..03f89a778 100644
--- a/internal/restorable/images.go
+++ b/internal/restorable/images.go
@@ -122,7 +122,7 @@ func RestoreIfNeeded(graphicsDriver graphicsdriver.Graphics) error {
 // DumpImages dumps all the current images to the specified directory.
 //
 // This is for testing usage.
-func DumpImages(graphicsDriver graphicsdriver.Graphics, dir string) error {
+func DumpImages(graphicsDriver graphicsdriver.Graphics, dir string) (string, error) {
 	images := make([]*graphicscommand.Image, 0, len(theImages.images))
 	for img := range theImages.images {
 		images = append(images, img.image)
diff --git a/internal/ui/image.go b/internal/ui/image.go
index e3e9703f2..819e2c927 100644
--- a/internal/ui/image.go
+++ b/internal/ui/image.go
@@ -89,11 +89,11 @@ func (i *Image) ReadPixels(pixels []byte, x, y, width, height int) {
 	}
 }
 
-func (i *Image) DumpScreenshot(name string, blackbg bool) error {
+func (i *Image) DumpScreenshot(name string, blackbg bool) (string, error) {
 	return theUI.dumpScreenshot(i.mipmap, name, blackbg)
 }
 
-func DumpImages(dir string) error {
+func DumpImages(dir string) (string, error) {
 	return theUI.dumpImages(dir)
 }
 
diff --git a/internal/ui/ui.go b/internal/ui/ui.go
index 57411f81e..bf9aed937 100644
--- a/internal/ui/ui.go
+++ b/internal/ui/ui.go
@@ -95,10 +95,10 @@ func (u *UserInterface) readPixels(mipmap *mipmap.Mipmap, pixels []byte, x, y, w
 	return mipmap.ReadPixels(u.graphicsDriver, pixels, x, y, width, height)
 }
 
-func (u *UserInterface) dumpScreenshot(mipmap *mipmap.Mipmap, name string, blackbg bool) error {
+func (u *UserInterface) dumpScreenshot(mipmap *mipmap.Mipmap, name string, blackbg bool) (string, error) {
 	return mipmap.DumpScreenshot(u.graphicsDriver, name, blackbg)
 }
 
-func (u *UserInterface) dumpImages(dir string) error {
+func (u *UserInterface) dumpImages(dir string) (string, error) {
 	return atlas.DumpImages(u.graphicsDriver, dir)
 }