diff --git a/crates/voicevox_core/src/engine/audio_file.rs b/crates/voicevox_core/src/engine/audio_file.rs
index f6facea6d..73f0b9cf1 100644
--- a/crates/voicevox_core/src/engine/audio_file.rs
+++ b/crates/voicevox_core/src/engine/audio_file.rs
@@ -9,7 +9,7 @@ pub(crate) fn to_wav<T: Float + From<i16> + From<f32> + Cast<i16>>(
     wave: &[T],
     audio_query: &AudioQueryModel,
 ) -> Vec<u8> {
-    // TODO: ライブラリ(e.g. https://docs.rs/hound)を使う
+    // TODO: ライブラリ(e.g. https://docs.rs/rubato & https://docs.rs/hound)を使う
 
     let volume_scale = *audio_query.volume_scale();
     let output_stereo = *audio_query.output_stereo();
diff --git a/crates/voicevox_core/src/engine/morph.rs b/crates/voicevox_core/src/engine/morph.rs
index ac5ae5eb5..1b5cb8338 100644
--- a/crates/voicevox_core/src/engine/morph.rs
+++ b/crates/voicevox_core/src/engine/morph.rs
@@ -39,12 +39,6 @@ impl<'metas> MorphableTargets<'metas> {
         audio_query: &AudioQueryModel,
         morph_rate: f64,
     ) -> crate::Result<Vec<u8>> {
-        if *audio_query.output_sampling_rate() != DEFAULT_SAMPLING_RATE
-            || *audio_query.output_stereo()
-        {
-            todo!();
-        }
-
         let waves = &self.get().try_map(|style_id| {
             synthesizer.synthesis_wave(audio_query, style_id, &Default::default())
         })?;