diff --git a/pkgs/tools/package-management/nix/default.nix b/pkgs/tools/package-management/nix/default.nix
index 2d105113133..b2cba0cc2d2 100644
--- a/pkgs/tools/package-management/nix/default.nix
+++ b/pkgs/tools/package-management/nix/default.nix
@@ -24,8 +24,8 @@ stdenv.mkDerivation rec {
   # would end up using the wrong bzip2 when cross-compiling.
   # XXX: The right thing would be to reinstate `--with-bzip2' in Nix.
   postUnpack =
-    '' export CPATH="${bzip2}/include"
-       export LIBRARY_PATH="${bzip2}/lib"
+    '' export CPATH="${bzip2.dev}/include"
+       export LIBRARY_PATH="${bzip2.out}/lib"
        export CXXFLAGS="-Wno-error=reserved-user-defined-literal"
     '';
 
diff --git a/pkgs/tools/package-management/nix/unstable.nix b/pkgs/tools/package-management/nix/unstable.nix
index 36d3d77c9f9..a87cde81c1a 100644
--- a/pkgs/tools/package-management/nix/unstable.nix
+++ b/pkgs/tools/package-management/nix/unstable.nix
@@ -22,8 +22,8 @@ stdenv.mkDerivation rec {
   # would end up using the wrong bzip2 when cross-compiling.
   # XXX: The right thing would be to reinstate `--with-bzip2' in Nix.
   postUnpack =
-    '' export CPATH="${bzip2}/include"
-       export LIBRARY_PATH="${bzip2}/lib"
+    '' export CPATH="${bzip2.dev}/include"
+       export LIBRARY_PATH="${bzip2.out}/lib"
        export CXXFLAGS="-Wno-error=reserved-user-defined-literal"
     '';