diff --git a/tests/fsharp/nunitConf.fs b/tests/fsharp/nunitConf.fs
index f0829ec08ac5713f4263bc84ec6f2c9873763f0b..1397b3ed778db815bfe596da89faa52d3cbc01ca 100644
--- a/tests/fsharp/nunitConf.fs
+++ b/tests/fsharp/nunitConf.fs
@@ -151,7 +151,7 @@ module Command =
             let fullpath = Commands.getfullpath dir
             match rt with 
             | Append p -> File.AppendText( p |> fullpath)
-            | Overwrite p -> new StreamWriter(File.OpenWrite(p |> fullpath))
+            | Overwrite p -> new StreamWriter(new FileStream(p |> fullpath, FileMode.Create))
 
         let outF fCont cmdArgs =
             match o with
diff --git a/tests/fsharp/test-framework.fs b/tests/fsharp/test-framework.fs
index df268ce3d41c3b5a576c6c5f6716fb0bd17faef2..4f16991968acde33fbec78ccee183165b3328179 100644
--- a/tests/fsharp/test-framework.fs
+++ b/tests/fsharp/test-framework.fs
@@ -395,7 +395,7 @@ module Command =
             let fullpath = Commands.getfullpath dir
             match rt with 
             | Append p -> File.AppendText( p |> fullpath)
-            | Overwrite p -> new StreamWriter(File.OpenWrite(p |> fullpath))
+            | Overwrite p -> new StreamWriter(new FileStream(p |> fullpath, FileMode.Create))
 
         let outF fCont cmdArgs =
             match redirect.Output with