diff --git a/_docs/index.tmpl.html b/_docs/index.tmpl.html
index 2a7aaa5fa..e189ec622 100644
--- a/_docs/index.tmpl.html
+++ b/_docs/index.tmpl.html
@@ -85,9 +85,7 @@ import (
 )
 
 func update(screen *ebiten.Image) error {
-        if err := ebitenutil.DebugPrint(screen, "Hello world!"); err != nil {
-                return err
-        }
+        ebitenutil.DebugPrint(screen, "Hello world!")
         return nil
 }
 
diff --git a/docs/examples/audio.html b/docs/examples/audio.html
index dcd4b225e..12d65f3fc 100644
--- a/docs/examples/audio.html
+++ b/docs/examples/audio.html
@@ -281,7 +281,9 @@ func main() {
         if err != nil {
                 log.Fatal(err)
         }
-        const sampleRate = 44100
+        // This sample rate doesn't match with wav/ogg's sample rate,
+        // but decoders adjust them.
+        const sampleRate = 48000
         const bytesPerSample = 4 // TODO: This should be defined in audio package
         audioContext, err = audio.NewContext(sampleRate)
         if err != nil {
diff --git a/docs/index.html b/docs/index.html
index 0726ca394..80b68fcad 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -117,9 +117,7 @@ import (
 )
 
 func update(screen *ebiten.Image) error {
-        if err := ebitenutil.DebugPrint(screen, "Hello world!"); err != nil {
-                return err
-        }
+        ebitenutil.DebugPrint(screen, "Hello world!")
         return nil
 }