diff --git a/src/libraries/Microsoft.PowerFx.Core/Binding/Binder.cs b/src/libraries/Microsoft.PowerFx.Core/Binding/Binder.cs
index d989c66859..47f5a247a0 100644
--- a/src/libraries/Microsoft.PowerFx.Core/Binding/Binder.cs
+++ b/src/libraries/Microsoft.PowerFx.Core/Binding/Binder.cs
@@ -2879,6 +2879,10 @@ public override void Visit(FirstNameNode node)
                     {
                         _txb.SetMutable(node, true);
                     }
+                    else if (lookupInfo.Data is IExternalDataSource ds)
+                    {
+                        _txb.SetMutable(node, ds.IsWritable);
+                    }
                 }
                 else if (lookupInfo.Kind == BindKind.ScopeCollection)
                 {
diff --git a/src/libraries/Microsoft.PowerFx.Core/Entities/External/IExternalDataSource.cs b/src/libraries/Microsoft.PowerFx.Core/Entities/External/IExternalDataSource.cs
index ed7791bb8a..fac6d91cac 100644
--- a/src/libraries/Microsoft.PowerFx.Core/Entities/External/IExternalDataSource.cs
+++ b/src/libraries/Microsoft.PowerFx.Core/Entities/External/IExternalDataSource.cs
@@ -18,6 +18,8 @@ internal interface IExternalDataSource : IExternalEntity, IExternalPageableSymbo
         bool IsRefreshable { get; }
 
         bool RequiresAsync { get; }
+        
+        bool IsWritable { get; }
 
         IExternalDataEntityMetadataProvider DataEntityMetadataProvider { get; }
 
diff --git a/src/tests/Microsoft.PowerFx.Core.Tests/AssociatedDataSourcesTests/TestDVEntity.cs b/src/tests/Microsoft.PowerFx.Core.Tests/AssociatedDataSourcesTests/TestDVEntity.cs
index 256d5b0eac..55e69e1694 100644
--- a/src/tests/Microsoft.PowerFx.Core.Tests/AssociatedDataSourcesTests/TestDVEntity.cs
+++ b/src/tests/Microsoft.PowerFx.Core.Tests/AssociatedDataSourcesTests/TestDVEntity.cs
@@ -29,6 +29,8 @@ public class AccountsEntity : IExternalEntity, IExternalDataSource
 
         public bool IsPageable => true;
 
+        public bool IsWritable => true;
+
         DType IExternalEntity.Type => AccountsTypeHelper.GetDType();
 
         IExternalDataEntityMetadataProvider IExternalDataSource.DataEntityMetadataProvider => throw new NotImplementedException();
diff --git a/src/tests/Microsoft.PowerFx.Core.Tests/Helpers/TestTabularDataSource.cs b/src/tests/Microsoft.PowerFx.Core.Tests/Helpers/TestTabularDataSource.cs
index c3a78e0a19..37e39381f2 100644
--- a/src/tests/Microsoft.PowerFx.Core.Tests/Helpers/TestTabularDataSource.cs
+++ b/src/tests/Microsoft.PowerFx.Core.Tests/Helpers/TestTabularDataSource.cs
@@ -218,6 +218,8 @@ internal TestDataSource(string name, DType schema, string[] keyColumns = null, I
 
         IDelegationMetadata IExternalDataSource.DelegationMetadata => DelegationMetadata;
 
+        public bool IsWritable => throw new NotImplementedException();
+
         public bool CanIncludeExpand(IExpandInfo expandToAdd)
         {
             throw new NotImplementedException();