diff --git a/backend/src/Squidex.Domain.Apps.Entities/Contents/GraphQL/Types/Assets/AssetGraphType.cs b/backend/src/Squidex.Domain.Apps.Entities/Contents/GraphQL/Types/Assets/AssetGraphType.cs
index 5e74d0e60..e5751ae77 100644
--- a/backend/src/Squidex.Domain.Apps.Entities/Contents/GraphQL/Types/Assets/AssetGraphType.cs
+++ b/backend/src/Squidex.Domain.Apps.Entities/Contents/GraphQL/Types/Assets/AssetGraphType.cs
@@ -246,7 +246,7 @@ internal sealed class AssetGraphType : SharedObjectGraphType<EnrichedAsset>
         AddField(new FieldType
         {
             Name = "sourceUrl",
-            ResolvedType = Scalars.NonNullString,
+            ResolvedType = Scalars.String,
             Resolver = SourceUrl,
             Description = FieldDescriptions.AssetSourceUrl
         });