diff --git a/Upsilon/BaseTypes/ScriptFunction.cs b/Upsilon/BaseTypes/ScriptFunction.cs
index 1180776..b4d0a2b 100644
--- a/Upsilon/BaseTypes/ScriptFunction.cs
+++ b/Upsilon/BaseTypes/ScriptFunction.cs
@@ -1,6 +1,4 @@
 using System;
-using System.Collections;
-using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Linq;
 using System.Reflection;
diff --git a/Upsilon/Upsilon.csproj b/Upsilon/Upsilon.csproj
index fd418ca..4f3fa9d 100644
--- a/Upsilon/Upsilon.csproj
+++ b/Upsilon/Upsilon.csproj
@@ -10,4 +10,8 @@
       </Reference>
     </ItemGroup>
 
+    <ItemGroup>
+      <PackageReference Include="System.Collections.Immutable" Version="1.5.0" />
+    </ItemGroup>
+
 </Project>