diff --git a/pkgs/build-support/writers/test.nix b/pkgs/build-support/writers/test.nix
index 005daf0be5b4..1b690e2d24c9 100644
--- a/pkgs/build-support/writers/test.nix
+++ b/pkgs/build-support/writers/test.nix
@@ -188,6 +188,7 @@ lib.recurseIntoAttrs {
     fsharp = expectSuccess (makeFSharpWriter {
       libraries = { fetchNuGet }: [
         (fetchNuGet { pname = "FSharp.SystemTextJson"; version = "0.17.4"; sha256 = "1bplzc9ybdqspii4q28l8gmfvzpkmgq5l1hlsiyg2h46w881lwg2"; })
+        (fetchNuGet { pname = "System.Text.Json"; version = "4.6.0"; sha256 = "0ism236hwi0k6axssfq58s1d8lihplwiz058pdvl8al71hagri39"; })
       ];
     } "test-writers-fsharp" ''
       #r "nuget: FSharp.SystemTextJson, 0.17.4"