diff --git a/pkgs/development/haskell-modules/lib.nix b/pkgs/development/haskell-modules/lib.nix
index 58d50592ac42..192a531e5d14 100644
--- a/pkgs/development/haskell-modules/lib.nix
+++ b/pkgs/development/haskell-modules/lib.nix
@@ -156,6 +156,9 @@ rec {
   addBuildDepend = drv: x: addBuildDepends drv [x];
   addBuildDepends = drv: xs: overrideCabal drv (drv: { buildDepends = (drv.buildDepends or []) ++ xs; });
 
+  addTestToolDepend = drv: x: addTestToolDepends drv [x];
+  addTestToolDepends = drv: xs: overrideCabal drv (drv: { testToolDepends = (drv.testToolDepends or []) ++ xs; });
+
   addPkgconfigDepend = drv: x: addPkgconfigDepends drv [x];
   addPkgconfigDepends = drv: xs: overrideCabal drv (drv: { pkgconfigDepends = (drv.pkgconfigDepends or []) ++ xs; });