diff --git a/pkgs/tools/graphics/netpbm/default.nix b/pkgs/tools/graphics/netpbm/default.nix
index 903c6336bcda..b5a46f22533d 100644
--- a/pkgs/tools/graphics/netpbm/default.nix
+++ b/pkgs/tools/graphics/netpbm/default.nix
@@ -1,6 +1,18 @@
-{ lib, stdenv, fetchsvn, pkgconfig, libjpeg, libpng, flex, zlib, perl, libxml2
-, makeWrapper, libtiff
-, enableX11 ? false, libX11 }:
+{ lib
+, stdenv
+, fetchsvn
+, pkgconfig
+, libjpeg
+, libpng
+, flex
+, zlib
+, perl
+, libxml2
+, makeWrapper
+, libtiff
+, enableX11 ? false
+, libX11
+}:
 
 stdenv.mkDerivation {
   # Determine version and revision from:
@@ -18,9 +30,20 @@ stdenv.mkDerivation {
       --replace '"-dSAFER"' '"-dPARANOIDSAFER"'
   '';
 
-  buildInputs =
-    [ pkgconfig flex zlib perl libpng libjpeg libxml2 makeWrapper libtiff ]
-    ++ lib.optional enableX11 libX11;
+  nativeBuildInputs = [
+    pkgconfig
+    flex
+    makeWrapper
+  ];
+
+  buildInputs = [
+    zlib
+    perl
+    libpng
+    libjpeg
+    libxml2
+    libtiff
+  ] ++ lib.optional enableX11 libX11;
 
   configurePhase = ''
     cp config.mk.in config.mk
@@ -30,7 +53,7 @@ stdenv.mkDerivation {
         --replace "TIFFHDR_DIR =" "TIFFHDR_DIR = ${libtiff.dev}/include" \
         --replace "JPEGLIB = NONE" "JPEGLIB = ${libjpeg.out}/lib/libjpeg.so" \
         --replace "JPEGHDR_DIR =" "JPEGHDR_DIR = ${libjpeg.dev}/include"
-   '' + stdenv.lib.optionalString stdenv.isDarwin ''
+  '' + stdenv.lib.optionalString stdenv.isDarwin ''
     echo "LDSHLIB=-dynamiclib -install_name $out/lib/libnetpbm.\$(MAJ).dylib" >> config.mk
     echo "NETPBMLIBTYPE = dylib" >> config.mk
     echo "NETPBMLIBSUFFIX = dylib" >> config.mk
@@ -64,9 +87,9 @@ stdenv.mkDerivation {
   passthru.updateScript = ./update.sh;
 
   meta = {
-    homepage = http://netpbm.sourceforge.net/;
+    homepage = "http://netpbm.sourceforge.net/";
     description = "Toolkit for manipulation of graphic images";
-    license = "GPL,free";
+    license = lib.licenses.free; # http://netpbm.svn.code.sourceforge.net/p/netpbm/code/trunk/doc/copyright_summary
     platforms = with stdenv.lib.platforms; linux ++ darwin;
   };
 }