diff --git a/back/src/Kyoo.Authentication/Kyoo.Authentication.csproj b/back/src/Kyoo.Authentication/Kyoo.Authentication.csproj
index b273ee03..9ce67f54 100644
--- a/back/src/Kyoo.Authentication/Kyoo.Authentication.csproj
+++ b/back/src/Kyoo.Authentication/Kyoo.Authentication.csproj
@@ -10,6 +10,7 @@
 		<PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
 
 		<ProjectReference Include="../Kyoo.Abstractions/Kyoo.Abstractions.csproj" />
+		<ProjectReference Include="../Kyoo.Core/Kyoo.Core.csproj" />
 	</ItemGroup>
 
 </Project>
diff --git a/back/src/Kyoo.Authentication/Views/AuthApi.cs b/back/src/Kyoo.Authentication/Views/AuthApi.cs
index caf7a5f8..59fd987f 100644
--- a/back/src/Kyoo.Authentication/Views/AuthApi.cs
+++ b/back/src/Kyoo.Authentication/Views/AuthApi.cs
@@ -19,7 +19,6 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
-using System.Linq;
 using System.Net.Http;
 using System.Net.Http.Json;
 using System.Text;
@@ -32,13 +31,11 @@ using Kyoo.Abstractions.Models.Permissions;
 using Kyoo.Abstractions.Models.Utils;
 using Kyoo.Authentication.Models;
 using Kyoo.Authentication.Models.DTO;
+using Kyoo.Core.Controllers;
 using Kyoo.Models;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.IdentityModel.Tokens;
-using Newtonsoft.Json;
-using Newtonsoft.Json.Converters;
-using Newtonsoft.Json.Linq;
 using static Kyoo.Abstractions.Models.Utils.Constants;
 using BCryptNet = BCrypt.Net.BCrypt;
 
@@ -51,7 +48,7 @@ namespace Kyoo.Authentication.Views
 	[Route("auth")]
 	[ApiDefinition("Authentication", Group = UsersGroup)]
 	public class AuthApi(
-		IRepository<User> users,
+		UserRepository users,
 		ITokenController tokenController,
 		IThumbnailsManager thumbs,
 		IHttpClientFactory clientFactory,
@@ -184,11 +181,8 @@ namespace Kyoo.Authentication.Views
 			User newUser = new();
 			if (profile.Email is not null)
 				newUser.Email = profile.Email;
-			if (profile.Username is not null)
-				newUser.Username = profile.Username;
-			else if (profile.Name is not null)
-				newUser.Username = profile.Name;
-			else
+			string? username = profile.Username ?? profile.Name;
+			if (username is null)
 			{
 				return BadRequest(
 					new RequestError(
@@ -196,12 +190,11 @@ namespace Kyoo.Authentication.Views
 					)
 				);
 			}
+			newUser.Username = username;
 			newUser.Slug = Utils.Utility.ToSlug(newUser.Username);
 			newUser.ExternalId.Add(provider, extToken);
 
-			User? user = await users.GetOrDefault(
-				new Filter<User>.Lambda(x => x.ExternalId[provider].Id == extToken.Id)
-			);
+			User? user = await users.GetByExternalId(provider, extToken.Id);
 			if (user == null)
 				user = await users.Create(newUser);
 			return new JwtToken(
diff --git a/back/src/Kyoo.Core/Controllers/Repositories/UserRepository.cs b/back/src/Kyoo.Core/Controllers/Repositories/UserRepository.cs
index c351a420..7cd219f9 100644
--- a/back/src/Kyoo.Core/Controllers/Repositories/UserRepository.cs
+++ b/back/src/Kyoo.Core/Controllers/Repositories/UserRepository.cs
@@ -18,6 +18,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Data.Common;
 using System.Linq;
 using System.Threading.Tasks;
 using Kyoo.Abstractions.Controllers;
@@ -35,10 +36,12 @@ namespace Kyoo.Core.Controllers;
 /// <remarks>
 /// Create a new <see cref="UserRepository"/>
 /// </remarks>
-/// <param name="database">The database handle to use</param>
-/// <param name="thumbs">The thumbnail manager used to store images.</param>
-public class UserRepository(DatabaseContext database, IThumbnailsManager thumbs)
-	: LocalRepository<User>(database, thumbs)
+public class UserRepository(
+	DatabaseContext database,
+	DbConnection db,
+	SqlVariableContext context,
+	IThumbnailsManager thumbs
+) : LocalRepository<User>(database, thumbs)
 {
 	/// <summary>
 	/// The database handle
@@ -84,4 +87,26 @@ public class UserRepository(DatabaseContext database, IThumbnailsManager thumbs)
 		await _database.SaveChangesAsync();
 		await base.Delete(obj);
 	}
+
+	public Task<User?> GetByExternalId(string provider, string id)
+	{
+		// language=PostgreSQL
+		return db.QuerySingle<User>(
+			$"""
+			select
+				u.* -- User as u
+				/* includes */
+			from
+				users as u
+			where
+				u.external_id->{provider}->>'id' = {id}
+			""",
+			new() { ["u"] = typeof(User) },
+			(items) => (items[0] as User)!,
+			context,
+			null,
+			null,
+			null
+		);
+	}
 }