diff --git a/app/islands/counter.tsx b/app/islands/counter.tsx
index 3e91a80f..c4420786 100644
--- a/app/islands/counter.tsx
+++ b/app/islands/counter.tsx
@@ -32,8 +32,8 @@ export default function Counter(props: InitialTime) {
       );
       const days = Math.floor(diffInSeconds / (60 * 60 * 24));
       // hoursを日本時間の24時間計算になるようにする
-      const hours = Math.floor((diffInSeconds / (60 * 60)) % 24) - 9;
-      hours < 0 ? hours + 24 : hours;
+      let hours = Math.floor((diffInSeconds / (60 * 60)) % 24) - 9;
+      hours < 0 ? (hours = hours + 24) : hours;
       const minutes = Math.floor((diffInSeconds / 60) % 60);
       const seconds = diffInSeconds % 60;
 
diff --git a/app/routes/index.tsx b/app/routes/index.tsx
index d716a014..90f0ad57 100644
--- a/app/routes/index.tsx
+++ b/app/routes/index.tsx
@@ -14,8 +14,8 @@ export default function Index() {
   const diffInSeconds = Math.floor((Number(nextBirthday) - Number(now)) / 1000);
   const days = Math.floor(diffInSeconds / (60 * 60 * 24));
   // hoursを日本時間の24時間計算になるようにする
-  const hours = Math.floor((diffInSeconds / (60 * 60)) % 24) - 9;
-  hours < 0 ? hours + 24 : hours;
+  let hours = Math.floor((diffInSeconds / (60 * 60)) % 24) - 9;
+  hours < 0 ? (hours = hours + 24) : hours;
   const minutes = Math.floor((diffInSeconds / 60) % 60);
   const seconds = diffInSeconds % 60;
 
diff --git a/biome.json b/biome.json
index 3ab017cf..54968582 100644
--- a/biome.json
+++ b/biome.json
@@ -23,7 +23,10 @@
   "linter": {
     "enabled": true,
     "rules": {
-      "recommended": true
+      "recommended": true,
+      "suspicious": {
+        "noAssignInExpressions": "off"
+      }
     }
   }
 }