diff --git a/audio/audio.go b/audio/audio.go
index 1547dcab8..569a128f0 100644
--- a/audio/audio.go
+++ b/audio/audio.go
@@ -250,10 +250,7 @@ func (c *Context) loop() {
 	// e.g. a variable for JVM on Android might not be set.
 	<-c.initCh
 
-	// The buffer size is 1/15 sec.
-	// It looks like 1/20 sec is too short for Android.
-	s := c.sampleRate * channelNum * bytesPerSample / 15
-	p, err := oto.NewPlayer(c.sampleRate, channelNum, bytesPerSample, s)
+	p, err := oto.NewPlayer(c.sampleRate, channelNum, bytesPerSample, c.bufferSize())
 	if err != nil {
 		c.errCh <- err
 		return
diff --git a/audio/buffersize.go b/audio/buffersize.go
new file mode 100644
index 000000000..70c469544
--- /dev/null
+++ b/audio/buffersize.go
@@ -0,0 +1,22 @@
+// Copyright 2017 The Ebiten Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build !js
+// +build !ios
+
+package audio
+
+func (c *Context) bufferSize() int {
+	return c.sampleRate * channelNum * bytesPerSample / 30
+}
diff --git a/audio/buffersize_ios.go b/audio/buffersize_ios.go
new file mode 100644
index 000000000..5c60e20b3
--- /dev/null
+++ b/audio/buffersize_ios.go
@@ -0,0 +1,22 @@
+// Copyright 2017 The Ebiten Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build ios
+
+package audio
+
+func (c *Context) bufferSize() int {
+	// TODO: Fix after oto uses HAL on Darwin.
+	return c.sampleRate * channelNum * bytesPerSample / 20
+}
diff --git a/audio/buffersize_js.go b/audio/buffersize_js.go
new file mode 100644
index 000000000..1a1399084
--- /dev/null
+++ b/audio/buffersize_js.go
@@ -0,0 +1,29 @@
+// Copyright 2017 The Ebiten Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build js
+
+package audio
+
+import (
+	"github.com/hajimehoshi/ebiten/internal/web"
+)
+
+func (c *Context) bufferSize() int {
+	n := 30
+	if web.IsMobileBrowser() {
+		n = 10
+	}
+	return c.sampleRate * channelNum * bytesPerSample / n
+}
diff --git a/internal/restorable/enabled_js.go b/internal/restorable/enabled_js.go
index d318fdbba..2013c900d 100644
--- a/internal/restorable/enabled_js.go
+++ b/internal/restorable/enabled_js.go
@@ -17,32 +17,11 @@
 package restorable
 
 import (
-	"strings"
-
-	"github.com/gopherjs/gopherjs/js"
+	"github.com/hajimehoshi/ebiten/internal/web"
 )
 
-func isIOS() bool {
-	ua := js.Global.Get("navigator").Get("userAgent").String()
-	if !strings.Contains(ua, "iPhone") {
-		return false
-	}
-	return true
-}
-
-func isAndroidChrome() bool {
-	ua := js.Global.Get("navigator").Get("userAgent").String()
-	if !strings.Contains(ua, "Android") {
-		return false
-	}
-	if !strings.Contains(ua, "Chrome") {
-		return false
-	}
-	return true
-}
-
 func init() {
-	if isIOS() || isAndroidChrome() {
+	if web.IsMobileBrowser() {
 		restoringEnabled = false
 	}
 }
diff --git a/internal/web/mobile.go b/internal/web/mobile.go
new file mode 100644
index 000000000..c9a2e4f5d
--- /dev/null
+++ b/internal/web/mobile.go
@@ -0,0 +1,46 @@
+// Copyright 2017 The Ebiten Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build js
+
+package web
+
+import (
+	"strings"
+
+	"github.com/gopherjs/gopherjs/js"
+)
+
+func isIOS() bool {
+	ua := js.Global.Get("navigator").Get("userAgent").String()
+	if !strings.Contains(ua, "iPhone") {
+		return false
+	}
+	return true
+}
+
+func isAndroidChrome() bool {
+	ua := js.Global.Get("navigator").Get("userAgent").String()
+	if !strings.Contains(ua, "Android") {
+		return false
+	}
+	if !strings.Contains(ua, "Chrome") {
+		return false
+	}
+	return true
+}
+
+func IsMobileBrowser() bool {
+	return isIOS() || isAndroidChrome()
+}