diff --git a/flake.nix b/flake.nix
index 7e69d15..eb4d272 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,6 +1,6 @@
 {
   description = "ghc.nix - the ghc devShell";
-  nixConfig.bash-prompt = "\\e[34;1mghc.nix ~ \\e[0m";
+  nixConfig.bash-prompt = "\\[\\e[34;1m\\]ghc.nix ~ \\[\\e[0m\\]";
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs/nixos-22.11";
     nixpkgs-unstable.url = "github:nixos/nixpkgs/nixpkgs-unstable";
diff --git a/ghc.nix b/ghc.nix
index ed6a929..17bb5b9 100644
--- a/ghc.nix
+++ b/ghc.nix
@@ -26,7 +26,7 @@ in
 , withDwarf ? (pkgsFor nixpkgs system).stdenv.isLinux  # enable libdw unwinding support
 , withNuma ? (pkgsFor nixpkgs system).stdenv.isLinux
 , withDtrace ? (pkgsFor nixpkgs system).stdenv.isLinux
-, withGrind ? true
+, withGrind ? !((pkgsFor nixpkgs system).valgrind.meta.broken or false)
 , withEMSDK ? false                    # load emscripten for js-backend
 }: