diff --git a/packages/backend/src/server/api/endpoints/notes/create.ts b/packages/backend/src/server/api/endpoints/notes/create.ts
index a0ed4bd816..b5b5dee113 100644
--- a/packages/backend/src/server/api/endpoints/notes/create.ts
+++ b/packages/backend/src/server/api/endpoints/notes/create.ts
@@ -111,7 +111,7 @@ export const paramDef = {
 		text: { type: "string", maxLength: MAX_NOTE_TEXT_LENGTH, nullable: true },
 		lang: {
 			type: "string",
-			enum: [null, ...Object.keys(langmap)],
+			enum: Object.keys(langmap),
 			nullable: true,
 		},
 		cw: { type: "string", nullable: true, maxLength: 100 },
diff --git a/packages/backend/src/server/api/endpoints/notes/edit.ts b/packages/backend/src/server/api/endpoints/notes/edit.ts
index 44892cb03c..fdb6ede385 100644
--- a/packages/backend/src/server/api/endpoints/notes/edit.ts
+++ b/packages/backend/src/server/api/endpoints/notes/edit.ts
@@ -171,7 +171,7 @@ export const paramDef = {
 		text: { type: "string", maxLength: MAX_NOTE_TEXT_LENGTH, nullable: true },
 		lang: {
 			type: "string",
-			enum: [null, ...Object.keys(langmap)],
+			enum: Object.keys(langmap),
 			nullable: true,
 		},
 		cw: { type: "string", nullable: true, maxLength: 250 },
diff --git a/packages/client/src/components/MkPostForm.vue b/packages/client/src/components/MkPostForm.vue
index a85b5481dd..a6d88dd645 100644
--- a/packages/client/src/components/MkPostForm.vue
+++ b/packages/client/src/components/MkPostForm.vue
@@ -992,7 +992,7 @@ async function post() {
 		channelId: props.channel ? props.channel.id : undefined,
 		poll: poll.value,
 		cw: useCw.value ? cw.value || "" : undefined,
-		lang: language.value,
+		lang: language.value ? language.value : undefined,
 		localOnly: localOnly.value,
 		visibility: visibility.value,
 		visibleUserIds: