diff --git a/backend/src/graphql/resolver/UserResolver.ts b/backend/src/graphql/resolver/UserResolver.ts
index ab49ee6bf..f6eccd7e8 100644
--- a/backend/src/graphql/resolver/UserResolver.ts
+++ b/backend/src/graphql/resolver/UserResolver.ts
@@ -276,7 +276,7 @@ export class UserResolver {
   }
 
   @Query(() => Boolean)
-  async checkUsername(@Args() { username }: CheckUsernameArgs): Promise<Boolean> {
+  async checkUsername(@Args() { username }: CheckUsernameArgs): Promise<boolean> {
     // Username empty?
     if (username === '') {
       throw new Error('Username must be set.')