diff --git a/FsBase/Extensions.fs b/FsBase/Extensions.fs
index a811410..4f7d868 100644
--- a/FsBase/Extensions.fs
+++ b/FsBase/Extensions.fs
@@ -1,6 +1,10 @@
 namespace FruityFoundation.FsBase
+open System.Collections.Generic
 open FruityFoundation.Base.Structures
 
+module Array =
+    let toReadOnlyCollection (a : 'a array) = a :> 'a IReadOnlyCollection
+
 module Option =
     let toMaybe : 'a option -> Maybe<'a> = function
         | Some x -> x |> Maybe.Just