diff --git a/pkgs/development/compilers/llvm/12/llvm/default.nix b/pkgs/development/compilers/llvm/12/llvm/default.nix
index 7ac5031c36bb..30a1a7a16df8 100644
--- a/pkgs/development/compilers/llvm/12/llvm/default.nix
+++ b/pkgs/development/compilers/llvm/12/llvm/default.nix
@@ -54,7 +54,8 @@ in stdenv.mkDerivation (rec {
   buildInputs = [ libxml2 libffi ]
     ++ optional enablePFM libpfm; # exegesis
 
-  propagatedBuildInputs = [ ncurses zlib ];
+  propagatedBuildInputs = optionals (stdenv.buildPlatform == stdenv.hostPlatform) [ ncurses ]
+    ++ [ zlib ];
 
   patches = [
     ./gnu-install-dirs.patch