diff --git a/packages/backend/src/server/api/endpoints/admin/decline-user.ts b/packages/backend/src/server/api/endpoints/admin/decline-user.ts
index 0a75dd977d..cefedb5bed 100644
--- a/packages/backend/src/server/api/endpoints/admin/decline-user.ts
+++ b/packages/backend/src/server/api/endpoints/admin/decline-user.ts
@@ -61,7 +61,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 					'Your Account has been declined!');
 			}
 
-			await this.usedUsernamesRepository.delete({ username: user.username });
+			await this.usedUsernamesRepository.delete({ username: user.username.toLowerCase() });
 
 			await this.deleteAccountService.deleteAccount(user);