diff --git a/pkgs/development/libraries/liblinear/default.nix b/pkgs/development/libraries/liblinear/default.nix
index e8d8e971bc54..7b70510dec3c 100644
--- a/pkgs/development/libraries/liblinear/default.nix
+++ b/pkgs/development/libraries/liblinear/default.nix
@@ -18,17 +18,19 @@ stdenv.mkDerivation rec {
     libSuff = stdenv.hostPlatform.extensions.sharedLibrary;
   in ''
     mkdir -p $out/lib $out/bin $out/include
-    cp liblinear.so.3 $out/lib/liblinear.3${libSuff}
-    ln -s $out/lib/liblinear.3${libSuff} $out/lib/liblinear${libSuff}
+    ${if stdenv.isDarwin then ''
+      cp liblinear.so.3 $out/lib/liblinear.3.dylib
+      ln -s $out/lib/liblinear.3.dylib $out/lib/liblinear.dylib
+      install_name_tool -id liblinear.3.dylib $out/lib/liblinear.3.dylib
+    '' else ''
+      cp liblinear.so.3 $out/lib/liblinear.so.3
+      ln -s $out/lib/liblinear.so.3 $out/lib/liblinear.so
+    ''}
     cp train $out/bin/liblinear-train
     cp predict $out/bin/liblinear-predict
     cp linear.h $out/include
   '';
 
-  postFixup = stdenv.lib.optionalString stdenv.isDarwin ''
-    install_name_tool -id liblinear.3.dylib $out/lib/liblinear.3.dylib
-  '';
-
   meta = with stdenv.lib; {
     description = "A library for large linear classification";
     homepage = https://www.csie.ntu.edu.tw/~cjlin/liblinear/;
diff --git a/pkgs/tools/security/nmap/default.nix b/pkgs/tools/security/nmap/default.nix
index 1b66dab35c8f..f88c533d71d3 100644
--- a/pkgs/tools/security/nmap/default.nix
+++ b/pkgs/tools/security/nmap/default.nix
@@ -1,24 +1,16 @@
 { stdenv, fetchurl, fetchpatch, libpcap, pkgconfig, openssl, lua5_3
+, pcre, liblinear, libssh2
 , graphicalSupport ? false
 , libX11 ? null
 , gtk2 ? null
-, withPython ? false # required for the `ndiff` binary
-, python2Packages ? null
+, python2 ? null
 , makeWrapper ? null
 , withLua ? true
 }:
 
-assert withPython -> python2Packages != null;
-
 with stdenv.lib;
 
-let
-
-  # Zenmap (the graphical program) also requires Python,
-  # so automatically enable pythonSupport if graphicalSupport is requested.
-  pythonSupport = withPython || graphicalSupport;
-
-in stdenv.mkDerivation rec {
+stdenv.mkDerivation rec {
   name = "nmap${optionalString graphicalSupport "-graphical"}-${version}";
   version = "7.80";
 
@@ -48,10 +40,7 @@ in stdenv.mkDerivation rec {
 
   configureFlags = [
     (if withLua then "--with-liblua=${lua5_3}" else "--without-liblua")
-  ]
-    ++ optional (!pythonSupport) "--without-ndiff"
-    ++ optional (!graphicalSupport) "--without-zenmap"
-    ;
+  ] ++ optionals (!graphicalSupport) [ "--without-ndiff" "--without-zenmap" ];
 
   makeFlags = optionals (stdenv.buildPlatform != stdenv.hostPlatform) [
     "AR=${stdenv.cc.bintools.targetPrefix}ar"
@@ -59,18 +48,22 @@ in stdenv.mkDerivation rec {
     "CC=${stdenv.cc.targetPrefix}gcc"
   ];
 
-  postInstall = optionalString pythonSupport ''
-      wrapProgram $out/bin/ndiff --prefix PYTHONPATH : "$(toPythonPath $out)" --prefix PYTHONPATH : "$PYTHONPATH"
-  '' + optionalString graphicalSupport ''
-      wrapProgram $out/bin/zenmap --prefix PYTHONPATH : "$(toPythonPath $out)" --prefix PYTHONPATH : "$PYTHONPATH" --prefix PYTHONPATH : $(toPythonPath $pygtk)/gtk-2.0 --prefix PYTHONPATH : $(toPythonPath $pygobject)/gtk-2.0 --prefix PYTHONPATH : $(toPythonPath $pycairo)/gtk-2.0
+  pythonPath = with python2.pkgs; optionals graphicalSupport  [
+    pygtk pysqlite pygobject2 pycairo
+  ];
+
+  nativeBuildInputs = [ pkgconfig ] ++ optionals graphicalSupport [ python2.pkgs.wrapPython ];
+  buildInputs = [ pcre liblinear libssh2 libpcap openssl ] ++ optionals graphicalSupport (with python2.pkgs; [
+    python2 libX11 gtk2
+  ]);
+
+  postInstall = optionalString graphicalSupport ''
+    buildPythonPath "$out $pythonPath"
+    patchPythonScript $out/bin/ndiff
+    patchPythonScript $out/bin/zenmap
   '';
 
-  nativeBuildInputs = [ pkgconfig ];
-  buildInputs = with python2Packages; [ libpcap openssl ]
-    ++ optionals pythonSupport [ makeWrapper python ]
-    ++ optionals graphicalSupport [
-      libX11 gtk2 pygtk pysqlite pygobject2 pycairo
-    ];
+  enableParallelBuilding = true;
 
   doCheck = false; # fails 3 tests, probably needs the net