diff --git a/pkgs/development/libraries/gtk+/3.x.nix b/pkgs/development/libraries/gtk+/3.x.nix
index 31bdba716b90..76424d79d7ad 100644
--- a/pkgs/development/libraries/gtk+/3.x.nix
+++ b/pkgs/development/libraries/gtk+/3.x.nix
@@ -8,11 +8,11 @@ assert xineramaSupport -> xlibs.libXinerama != null;
 assert cupsSupport -> cups != null;
 
 stdenv.mkDerivation rec {
-  name = "gtk+-3.8.2";
+  name = "gtk+-3.8.4";
 
   src = fetchurl {
     url = "mirror://gnome/sources/gtk+/3.8/${name}.tar.xz";
-    sha256 = "15zjmyky4yw70ipi12dllira4av8wjpw5f7g9kbrbpx12nf0ra0w";
+    sha256 = "1qlj0qdhkp8j5xiris4l4xnx47g4pbk4qnj3nf8rwa82fwb610xh";
   };
 
   enableParallelBuilding = true;
@@ -45,7 +45,7 @@ stdenv.mkDerivation rec {
 
     license = "LGPLv2+";
 
-    maintainers = with stdenv.lib.maintainers; [urkud raskin];
+    maintainers = with stdenv.lib.maintainers; [ urkud raskin vcunat];
     platforms = stdenv.lib.platforms.all;
   };
 }
diff --git a/pkgs/development/libraries/libpng/default.nix b/pkgs/development/libraries/libpng/default.nix
index ec24f1fca970..23d4ce8ce713 100644
--- a/pkgs/development/libraries/libpng/default.nix
+++ b/pkgs/development/libraries/libpng/default.nix
@@ -3,9 +3,9 @@
 assert zlib != null;
 
 let
-  version = "1.6.3";
-  sha256 = "0i8gz8mbkygc0ny7aa2i2wiavysxy6fdaphl52l49fb3hv9w1v65";
-  patch_src = fetchurl {
+  version = "1.6.4";
+  sha256 = "15pqany43q2hzaxqn84p9dba071xmvqi8h1bhnjxnxdf3g64zayg";
+  patch_src = throw "apng patch not yet released" fetchurl {
     url = "mirror://sourceforge/libpng-apng/libpng-${version}-apng.patch.gz";
     sha256 = "0fjnb6cgbj2c7ggl0qzcnliml2ylrjxzigp89vw0hxq221k5mlsx";
   };
@@ -27,10 +27,11 @@ in stdenv.mkDerivation rec {
 
   passthru = { inherit zlib; };
 
-  meta = {
+  meta = with stdenv.lib; {
     description = "The official reference implementation for the PNG file format" + whenPatched " with animation patch";
     homepage = http://www.libpng.org/pub/png/libpng.html;
     license = "free-non-copyleft"; # http://www.libpng.org/pub/png/src/libpng-LICENSE.txt
-    platforms = stdenv.lib.platforms.all;
+    platforms = platforms.all;
+    maintainers = [ maintainers.vcunat ];
   };
 }
diff --git a/pkgs/development/libraries/mesa/default.nix b/pkgs/development/libraries/mesa/default.nix
index a361f06e4ba9..4fa5ee9e74ae 100644
--- a/pkgs/development/libraries/mesa/default.nix
+++ b/pkgs/development/libraries/mesa/default.nix
@@ -24,6 +24,7 @@ else
 
 let
   version = "9.1.6";
+  # this is the default search path for DRI drivers (note: X server introduces an overriding env var)
   driverLink = "/run/opengl-driver" + stdenv.lib.optionalString stdenv.isi686 "-32";
 in
 stdenv.mkDerivation {
@@ -134,6 +135,8 @@ stdenv.mkDerivation {
         patchelf --set-rpath "$(patchelf --print-rpath $lib):$drivers/lib" "$lib"
       fi
     done
+  '' + /* set the default search path for DRI drivers; used e.g. by X server */ ''
+    substituteInPlace "$out/lib/pkgconfig/dri.pc" --replace '$(drivers)' "${driverLink}"
   '';
   #ToDo: @vcunat isn't sure if drirc will be found when in $out/etc/, but it doesn't seem important ATM