diff --git a/src/Tgstation.Server.Host/Security/OAuth/IOAuthValidator.cs b/src/Tgstation.Server.Host/Security/OAuth/IOAuthValidator.cs
index 402fb5efe7..472a7ff091 100644
--- a/src/Tgstation.Server.Host/Security/OAuth/IOAuthValidator.cs
+++ b/src/Tgstation.Server.Host/Security/OAuth/IOAuthValidator.cs
@@ -3,8 +3,6 @@ using System.Threading.Tasks;
 
 using Tgstation.Server.Api.Models;
 
-#nullable disable
-
 namespace Tgstation.Server.Host.Security.OAuth
 {
 	/// <summary>
@@ -29,6 +27,6 @@ namespace Tgstation.Server.Host.Security.OAuth
 		/// <param name="code">The OAuth response string from web application.</param>
 		/// <param name="cancellationToken">The <see cref="CancellationToken"/> for the operation.</param>
 		/// <returns>A <see cref="ValueTask{TResult}"/> resulting in <see langword="null"/> if authentication failed, <see cref="global::System.UInt64.MaxValue"/> if a rate limit occurred, and the validated <see cref="OAuthConnection.ExternalUserId"/> otherwise.</returns>
-		ValueTask<string> ValidateResponseCode(string code, CancellationToken cancellationToken);
+		ValueTask<string?> ValidateResponseCode(string code, CancellationToken cancellationToken);
 	}
 }