tests.haskell.setBuildTarget: prevent unnecessary rebuilds

1 files changed, 9 insertions, 1 deletions

diff --git a/pkgs/test/haskell/setBuildTarget/default.nix b/pkgs/test/haskell/setBuildTarget/default.nix
index f0c78c5104499..39d5db698bcd0 100644
--- a/pkgs/test/haskell/setBuildTarget/default.nix
+++ b/pkgs/test/haskell/setBuildTarget/default.nix
@@ -7,7 +7,15 @@ let
       mkDerivation {
         pname = "haskell-setBuildTarget";
         version = "0.1.0.0";
-        src = ./.;
+        src = lib.fileset.toSource {
+          root = ./.;
+          fileset = lib.fileset.unions [
+            ./haskell-setBuildTarget.cabal
+            ./Bar.hs
+            ./Foo.hs
+            ./Setup.hs
+          ];
+        };
         isLibrary = false;
         isExecutable = true;
         executableHaskellDepends = [ base ];