diff --git a/CHANGELOG.md b/CHANGELOG.md
index cb8ab8f30f..a063006566 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 d10f690a32..8f5e6177c2 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 c9ff02cc76..c3b777a12e 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;
 }