diff --git a/tests/SqlClient.Tests/TVPTests.fs b/tests/SqlClient.Tests/TVPTests.fs
index 4bae1bf0..7d2b86f8 100644
--- a/tests/SqlClient.Tests/TVPTests.fs
+++ b/tests/SqlClient.Tests/TVPTests.fs
@@ -4,7 +4,7 @@ open FSharp.Data.SqlClient
 #else
 module FSharp.Data.SqlClient.TVPTests
 #endif
-
+open System
 open FSharp.Data
 open Xunit
 
@@ -238,4 +238,62 @@ let ``User Defined Table Types should list columns orderd by Column Id (i.e. the
     |> Seq.map (fun (i, s, b) -> TestTVPColumnOrder.TVPColumnOrder(i, s, b))
     |> Seq.toList
     |> cmd.Execute
-    |> ignore
\ No newline at end of file
+    |> ignore
+
+
+type AddSqlCommandIssue424 = SqlCommandProvider<"
+insert [testtable_424]
+(
+    c1,
+    c2,
+    c11,
+    c4,
+    c3,
+    c5,
+    c6,
+    c7,
+    c8,
+    c9,
+    c10
+)
+select
+    @c1,
+    @c2,
+    @c11,
+    @c4,
+    x.c3,
+    x.c5,
+    x.c6,
+    x.c7,
+    x.c8,
+    x.c9,
+    x.c10
+from @c12 x;
+" , ConnectionStrings.AdventureWorksLiteral, TableVarMapping = "@c12=testtable_424_item">
+
+[<Fact>]
+let ``Issue #424 conversion failed when using UDTT`` () =
+    use cmd = new AddSqlCommandIssue424(ConnectionStrings.AdventureWorksLiteral)
+    
+    let items =
+        [
+            AddSqlCommandIssue424.testtable_424_item(
+                c3 = Guid.NewGuid(),
+                c5 = "TestName",
+                c6 = Some "C6",
+                c7 = "C7",
+                c8 = 1,
+                c9 = "C9",
+                c10 = Guid.NewGuid()
+            )
+        ]
+    
+    let r =
+        cmd.Execute(
+            c1 = Guid.NewGuid(),
+            c2 = Guid.NewGuid(),
+            c4 = "C4 Name",
+            c11 = Guid.NewGuid(),
+            c12 = items
+        )
+    ()
\ No newline at end of file
diff --git a/tests/SqlClient.Tests/extensions.sql b/tests/SqlClient.Tests/extensions.sql
index 33a709ad..b315a7f4 100644
--- a/tests/SqlClient.Tests/extensions.sql
+++ b/tests/SqlClient.Tests/extensions.sql
@@ -439,3 +439,42 @@ begin
     select created_at from @tvp
 end
 go
+
+
+-- issue #424
+if object_id('dbo.testtable_424') is not null
+	drop table dbo.testtable_424
+go
+
+create table testtable_424 (
+	c1 uniqueidentifier not null,
+	c2 uniqueidentifier not null,
+	c3 uniqueidentifier not null,
+
+	c4 nvarchar(100) not null,
+	c5 nvarchar(100) not null,
+	c6 nvarchar(100) null,
+	c7 nvarchar(1000) not null,
+
+	c8 int not null,
+
+	c9 varchar(10) not null,
+	c10 uniqueidentifier not null,
+	c11 uniqueidentifier not null,
+
+	constraint pk_id_testtable_424 primary key clustered(c1, c2, c3)
+);
+
+if type_id('dbo.testtable_424_item') is not null
+	drop type dbo.testtable_424_item
+go
+
+create type dbo.testtable_424_item as table(
+	c3 uniqueidentifier not null,
+	c5 nvarchar(100) not null,
+	c6 nvarchar(100) null,
+	c7 nvarchar(1000) not null,
+	c8 int not null,
+	c9 varchar(10) not null,
+	c10 uniqueidentifier not null
+);