diff --git a/packages/backend/src/server/api/endpoints/i/update.ts b/packages/backend/src/server/api/endpoints/i/update.ts
index 7b900a74..a3d5f4d6 100644
--- a/packages/backend/src/server/api/endpoints/i/update.ts
+++ b/packages/backend/src/server/api/endpoints/i/update.ts
@@ -160,7 +160,7 @@ export default define(meta, paramDef, async (ps, _user, token) => {
 
 	if (ps.name !== undefined) updates.name = ps.name;
 	if (ps.description !== undefined) profileUpdates.description = ps.description;
-	if (ps.lang !== undefined) profileUpdates.lang = ps.lang;
+	if (typeof ps.lang === "string") profileUpdates.lang = ps.lang;
 	if (ps.location !== undefined) profileUpdates.location = ps.location;
 	if (ps.birthday !== undefined) profileUpdates.birthday = ps.birthday;
 	if (ps.ffVisibility !== undefined)
@@ -189,7 +189,7 @@ export default define(meta, paramDef, async (ps, _user, token) => {
 		profileUpdates.mutedInstances = ps.mutedInstances;
 	if (ps.mutingNotificationTypes !== undefined)
 		profileUpdates.mutingNotificationTypes =
-			ps.mutingNotificationTypes as typeof notificationTypes[number][];
+			ps.mutingNotificationTypes as (typeof notificationTypes)[number][];
 	if (typeof ps.isLocked === "boolean") updates.isLocked = ps.isLocked;
 	if (typeof ps.isExplorable === "boolean")
 		updates.isExplorable = ps.isExplorable;