diff --git a/CHANGELOG.md b/CHANGELOG.md
index cb8ab8f30..a06300656 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -48,6 +48,7 @@
 - Fix: 無効化されたアンテナにアクセスがあった際に再度有効化するように
 - Fix: お知らせの画像URLを空にできない問題を修正
 - Fix: i/notificationsのsinceIdが機能しない問題を修正
+- Fix: pageのピン留めを解除することができない問題を修正
 
 ## 13.12.2
 
diff --git a/packages/backend/src/server/api/endpoints/i/update.ts b/packages/backend/src/server/api/endpoints/i/update.ts
index d10f690a3..8f5e6177c 100644
--- a/packages/backend/src/server/api/endpoints/i/update.ts
+++ b/packages/backend/src/server/api/endpoints/i/update.ts
@@ -146,7 +146,7 @@ export const paramDef = {
 		alwaysMarkNsfw: { type: 'boolean' },
 		autoSensitive: { type: 'boolean' },
 		ffVisibility: { type: 'string', enum: ['public', 'followers', 'private'] },
-		pinnedPageId: { type: 'string', format: 'misskey:id' },
+		pinnedPageId: { type: 'string', format: 'misskey:id', nullable: true },
 		mutedWords: { type: 'array' },
 		mutedInstances: { type: 'array', items: {
 			type: 'string',
diff --git a/packages/frontend/src/components/MkUserPopup.vue b/packages/frontend/src/components/MkUserPopup.vue
index c9ff02cc7..c3b777a12 100644
--- a/packages/frontend/src/components/MkUserPopup.vue
+++ b/packages/frontend/src/components/MkUserPopup.vue
@@ -22,7 +22,7 @@
 				<div :class="$style.username"><MkAcct :user="user"/></div>
 			</div>
 			<div :class="$style.description">
-				<Mfm v-if="user.description" :text="user.description" :author="user" :i="$i"/>
+				<Mfm v-if="user.description" :class="$style.mfm" :text="user.description" :author="user" :i="$i"/>
 				<div v-else style="opacity: 0.7;">{{ i18n.ts.noAccountDescription }}</div>
 			</div>
 			<div :class="$style.status">
@@ -192,6 +192,13 @@ onMounted(() => {
 	border-bottom: solid 1px var(--divider);
 }
 
+.mfm {
+	display: -webkit-box;
+	-webkit-line-clamp: 5;
+	-webkit-box-orient: vertical;  
+	overflow: hidden;
+}
+
 .status {
 	padding: 16px 26px 16px 26px;
 }