diff --git a/Makefile b/Makefile
index abfb1e3..978005e 100644
--- a/Makefile
+++ b/Makefile
@@ -3,6 +3,8 @@ fmt:
 	cargo fmt --all
 lint:
 	cargo +nightly clippy --all --all-targets --all-features --fix -Z unstable-options --allow-dirty --allow-staged
+hack:
+	cargo hack check --each-feature --no-dev-deps --all
 test:
 	cargo test --all-features
 watch:
diff --git a/src/handler/mod.rs b/src/handler/mod.rs
index 5c1246a..bd4c836 100644
--- a/src/handler/mod.rs
+++ b/src/handler/mod.rs
@@ -107,7 +107,6 @@ impl EventHandler for Handler {
         new_voice_state: voice::VoiceState,
     ) {
         let state = CurrentVoiceState::new(new_voice_state);
-        #[cfg(feature = "tts")]
         let change = state.change_of_states(old_voice_state.as_ref());
         let member = state.voice_member().await.expect("member is not received");
         let voice = Voice::from(&ctx, member.guild_id).await;
diff --git a/src/handler/usecase/text_to_speech/text_to_speech_base.rs b/src/handler/usecase/text_to_speech/text_to_speech_base.rs
index a5f0157..66d7c25 100644
--- a/src/handler/usecase/text_to_speech/text_to_speech_base.rs
+++ b/src/handler/usecase/text_to_speech/text_to_speech_base.rs
@@ -1,7 +1,10 @@
+#[cfg(feature = "tts")]
 use super::super::interface::Speaker;
+#[cfg(feature = "tts")]
 use super::config;
 #[cfg(feature = "tts")]
 use super::text_to_speech_message::Message;
+#[cfg(feature = "tts")]
 use crate::infrastructure::GuildPath;
 
 #[derive(Debug, PartialEq, Eq)]
diff --git a/src/model/message.rs b/src/model/message.rs
index eed4ed9..05813af 100644
--- a/src/model/message.rs
+++ b/src/model/message.rs
@@ -1,6 +1,9 @@
+#[cfg(feature = "tts")]
 use serenity::model::channel::Message as SerenityMessage;
+#[cfg(feature = "tts")]
 use std::env;
 
+#[cfg(feature = "tts")]
 pub struct Message {
     pub msg: SerenityMessage,
 }