diff --git a/pkgs/applications/science/math/R/default.nix b/pkgs/applications/science/math/R/default.nix
index 815d108ce412..d08078c356e1 100644
--- a/pkgs/applications/science/math/R/default.nix
+++ b/pkgs/applications/science/math/R/default.nix
@@ -35,7 +35,7 @@ stdenv.mkDerivation rec {
 
   # Test of the examples for package 'tcltk' fails in Darwin sandbox. See:
   # https://github.com/NixOS/nixpkgs/issues/146131
-  prePatch = lib.optionalString stdenv.isDarwin ''
+  postPatch = lib.optionalString stdenv.isDarwin ''
     substituteInPlace configure \
       --replace "-install_name libRblas.dylib" "-install_name $out/lib/R/lib/libRblas.dylib" \
       --replace "-install_name libRlapack.dylib" "-install_name $out/lib/R/lib/libRlapack.dylib" \