1diff --git a/src/scripts/scriptlib.fsx b/src/scripts/scriptlib.fsx
2index cc797e305..5a7be7d2b 100644
3--- a/src/scripts/scriptlib.fsx
4+++ b/src/scripts/scriptlib.fsx
5@@ -36,7 +36,7 @@ module Scripting =
6 #if INTERACTIVE
7 let argv = Microsoft.FSharp.Compiler.Interactive.Settings.fsi.CommandLineArgs |> Seq.skip 1 |> Seq.toArray
8
9- let getCmdLineArgOptional switchName =
10+ let getCmdLineArgOptional (switchName: string) =
11 argv |> Array.filter(fun t -> t.StartsWith(switchName)) |> Array.map(fun t -> t.Remove(0, switchName.Length).Trim()) |> Array.tryHead
12
13 let getCmdLineArg switchName defaultValue =