diff --git a/functions/api/v1/apps.ts b/functions/api/v1/apps.ts
index 2afa1a1..e28b5bc 100644
--- a/functions/api/v1/apps.ts
+++ b/functions/api/v1/apps.ts
@@ -1,5 +1,6 @@
 import { ContextData } from 'wildebeest/backend/src/types/context'
 import { cors } from 'wildebeest/backend/src/utils/cors'
+import * as errors from 'wildebeest/backend/src/errors'
 import type { JWK } from 'wildebeest/backend/src/webpush/jwk'
 import type { Env } from 'wildebeest/backend/src/types/env'
 import { createClient } from 'wildebeest/backend/src/mastodon/client'
@@ -25,22 +26,22 @@ export async function handleRequest(db: D1Database, request: Request, vapidKeys:
 
 	const body: AppsPost = await readBody<AppsPost>(request)
 
-  // Parameter validation according to https://github.com/mastodon/mastodon/blob/main/app/lib/application_extension.rb
-  if ((body.client_name === undefined) || (body.client_name?.trim() === '')) {
-    return new Response('Unprocessable entity: client_name cannot be an empty string', { status: 422 })
-  } else if ((body.client_name?.length > 60)) {
-    return new Response('Unprocessable entity: client_name cannot exceed 60 characters', { status: 422 })
-  } else if ((body.redirect_uris === undefined) || (body.redirect_uris?.trim() === '')) {
-    return new Response('Unprocessable entity: redirect_uris cannot be an empty string', { status: 422 })
-  } else if ((body.redirect_uris?.length > 2000)) {
-    return new Response('Unprocessable entity: redirect_uris cannot exceed 2000 characters', { status: 422 })
-  } else if (body.redirect_uris !== 'urn:ietf:wg:oauth:2.0:oob') {
-    try {
-      new URL("", body.redirect_uris);
-    } catch {
-      return new Response('Unprocessable entity: redirect_uris must be a valid URI', { status: 422 })
-    }
-  }
+	// Parameter validation according to https://github.com/mastodon/mastodon/blob/main/app/lib/application_extension.rb
+	if (body.client_name === undefined || body.client_name?.trim() === '') {
+    return errors.unprocessableEntity('client_name cannot be an empty string')
+	} else if (body.client_name?.length > 60) {
+    return errors.unprocessableEntity('client_name cannot exceed 60 characters')
+	} else if (body.redirect_uris === undefined || body.redirect_uris?.trim() === '') {
+    return errors.unprocessableEntity('redirect_uris cannot be an empty string')
+	} else if (body.redirect_uris?.length > 2000) {
+    return errors.unprocessableEntity('redirect_uris cannot exceed 2000 characters')
+	} else if (body.redirect_uris !== 'urn:ietf:wg:oauth:2.0:oob') {
+		try {
+			new URL('', body.redirect_uris)
+		} catch {
+      return errors.unprocessableEntity('redirect_uris must be a valid URI')
+		}
+	}
 
 	const client = await createClient(db, body.client_name, body.redirect_uris, body.website, body.scopes)
 	const vapidKey = VAPIDPublicKey(vapidKeys)