diff --git a/locales/ja-JP.yml b/locales/ja-JP.yml
index e4de19cca7..6804b35c7a 100644
--- a/locales/ja-JP.yml
+++ b/locales/ja-JP.yml
@@ -1237,7 +1237,7 @@ desktop/views/pages/user/user.header.vue:
   following: "フォロー"
   followers: "フォロワー"
   is-bot: "このアカウントはBotです"
-  years-old: "歳"
+  years-old: "{age}歳"
   year: "年"
   month: "月"
   day: "日"
@@ -1543,6 +1543,7 @@ mobile/views/pages/user.vue:
   unmute: "ミュート解除"
   block: "ブロック"
   unblock: "ブロック解除"
+  years-old: "{age}歳"
 
 mobile/views/pages/user/home.vue:
   recent-notes: "最近の投稿"
diff --git a/src/client/app/desktop/views/pages/user/user.header.vue b/src/client/app/desktop/views/pages/user/user.header.vue
index a2f3f183b8..48b5a487f4 100644
--- a/src/client/app/desktop/views/pages/user/user.header.vue
+++ b/src/client/app/desktop/views/pages/user/user.header.vue
@@ -18,7 +18,7 @@
 		</div>
 		<div class="info">
 			<span class="location" v-if="user.host === null && user.profile.location"><fa icon="map-marker"/> {{ user.profile.location }}</span>
-			<span class="birthday" v-if="user.host === null && user.profile.birthday"><fa icon="birthday-cake"/> {{ user.profile.birthday.replace('-', this.$t('year')).replace('-', this.$t('month')) + this.$t('day') }} ({{ age }}%i18n:@years-old%)</span>
+			<span class="birthday" v-if="user.host === null && user.profile.birthday"><fa icon="birthday-cake"/> {{ user.profile.birthday.replace('-', $t('year')).replace('-', $t('month')) + $t('day') }} ({{ $t('years-old', { age }) }})</span>
 		</div>
 		<div class="status">
 			<span class="notes-count"><b>{{ user.notesCount | number }}</b>{{ $t('posts') }}</span>
diff --git a/src/client/app/mobile/views/pages/user.vue b/src/client/app/mobile/views/pages/user.vue
index 7ac6e17723..c88cbe6813 100644
--- a/src/client/app/mobile/views/pages/user.vue
+++ b/src/client/app/mobile/views/pages/user.vue
@@ -27,7 +27,7 @@
 						<fa icon="map-marker"/>{{ user.profile.location }}
 					</p>
 					<p class="birthday" v-if="user.host === null && user.profile.birthday">
-						<fa icon="birthday-cake"/>{{ user.profile.birthday.replace('-', '年').replace('-', '月') + '日' }} ({{ age }}歳)
+						<fa icon="birthday-cake"/>{{ user.profile.birthday.replace('-', '年').replace('-', '月') + '日' }} ({{ $t('years-old', { age }) }})
 					</p>
 				</div>
 				<div class="status">