diff --git a/packages/client/src/i18n.ts b/packages/client/src/i18n.ts
index 823900677..49fb1423b 100644
--- a/packages/client/src/i18n.ts
+++ b/packages/client/src/i18n.ts
@@ -33,7 +33,7 @@ class I18n<T extends Record<string, any>> {
 		// Perform string interpolation.
 		if (args) {
 			for (const [k, v] of Object.entries(args)) {
-				str = str.replace(`{${k}}`, v.toString());
+				str = str.replace(`{${k}}`, v?.toString());
 			}
 		}
 
diff --git a/packages/client/src/pages/note.vue b/packages/client/src/pages/note.vue
index 412142433..1c351c5c2 100644
--- a/packages/client/src/pages/note.vue
+++ b/packages/client/src/pages/note.vue
@@ -127,7 +127,7 @@ definePageMetadata(computed(() => note ? {
 	avatar: note.user,
 	path: `/notes/${note.id}`,
 	share: {
-		title: i18n.t('noteOf', { user: note.user.name }),
+		title: i18n.t('noteOf', { user: note.user.name || note.user.username }),
 		text: note.text,
 	},
 } : null));
diff --git a/packages/client/src/scripts/get-note-menu.ts b/packages/client/src/scripts/get-note-menu.ts
index d265285a0..57445a49a 100644
--- a/packages/client/src/scripts/get-note-menu.ts
+++ b/packages/client/src/scripts/get-note-menu.ts
@@ -183,7 +183,7 @@ export function getNoteMenu(props: {
 
 	function share(): void {
 		navigator.share({
-			title: i18n.t('noteOf', { user: appearNote.user.name }),
+			title: i18n.t('noteOf', { user: appearNote.user.name || appearNote.user.username }),
 			text: appearNote.text,
 			url: `${url}/notes/${appearNote.id}`,
 		});