diff --git a/pkgs/development/libraries/mesa/default.nix b/pkgs/development/libraries/mesa/default.nix
index f1dc316902f..1b2bb06ac2c 100644
--- a/pkgs/development/libraries/mesa/default.nix
+++ b/pkgs/development/libraries/mesa/default.nix
@@ -1,13 +1,8 @@
 {stdenv, fetchurl, pkgconfig, x11, xlibs, libdrm, expat}:
 
-let
-
-  target =
-    if stdenv.system == "i686-linux" then "linux-dri-x86" else
-    if stdenv.system == "x86_64-linux" then "linux-dri-x86-64" else
-    abort "unsupported platform for Mesa"; # !!! change to throw, remove all the mesa asserts in all-packages.nix
-
-in
+if stdenv.system != "i686-linux" && stdenv.system != "x86_64-linux" then
+  throw "unsupported platform for Mesa"
+else
 
 stdenv.mkDerivation {
   name = "mesa-7.4.1";
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 3c8467aedd5..c3aea54d1a1 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -700,7 +700,7 @@ let
     inherit (xlibs) xproto libXt libX11;
   };
 
-  glxinfo = assert mesaSupported; import ../tools/graphics/glxinfo {
+  glxinfo = import ../tools/graphics/glxinfo {
     inherit fetchurl stdenv x11 mesa;
   };
 
@@ -2972,7 +2972,7 @@ let
     inherit fetchurl stdenv openal;
   };
 
-  freeglut = assert mesaSupported; import ../development/libraries/freeglut {
+  freeglut = import ../development/libraries/freeglut {
     inherit fetchurl stdenv x11 mesa;
   };
 
@@ -3320,7 +3320,7 @@ let
     inherit fetchurl stdenv libcddb pkgconfig ncurses help2man;
   };
 
-  libcm = assert mesaSupported; import ../development/libraries/libcm {
+  libcm = import ../development/libraries/libcm {
     inherit fetchurl stdenv pkgconfig xlibs mesa;
     inherit (gtkLibs) glib;
   };
@@ -3654,7 +3654,7 @@ let
     system == "i686-linux" ||
     system == "x86_64-linux";
 
-  mesa = assert mesaSupported; import ../development/libraries/mesa {
+  mesa = import ../development/libraries/mesa {
     inherit fetchurl stdenv pkgconfig expat x11 xlibs libdrm;
   };
 
@@ -7886,7 +7886,7 @@ let
     inherit (gnome) esound;
   };
 
-  compiz_050 = assert mesaSupported; import ../applications/window-managers/compiz/0.5.0.nix {
+  compiz_050 = import ../applications/window-managers/compiz/0.5.0.nix {
     inherit fetchurl stdenv pkgconfig libpng mesa;
     inherit (xorg) libXcomposite libXfixes libXdamage libXrandr
       libXinerama libICE libSM libXrender xextproto;
@@ -7903,7 +7903,7 @@ let
     version = "0.6.2";
   };
 
-  compizBase = composedArgsAndFun (assert mesaSupported; selectVersion ../applications/window-managers/compiz "0.8.0") {
+  compizBase = composedArgsAndFun (selectVersion ../applications/window-managers/compiz "0.8.0") {
     inherit lib builderDefs stringsWithDeps;
     inherit fetchurl stdenv pkgconfig libpng mesa perl perlXMLParser libxslt gettext
       intltool;
@@ -7926,7 +7926,7 @@ let
     extraConfigureFlags = getConfig ["compiz" "extraConfigureFlags"] [];
   };
 
-  compizFusion = assert mesaSupported; import ../applications/window-managers/compiz-fusion {
+  compizFusion = import ../applications/window-managers/compiz-fusion {
     version = getConfig ["compizFusion" "version"] "0.7.8";
     inherit compiz;
     inherit stringsWithDeps lib builderDefs;
@@ -8296,7 +8296,7 @@ let
     inherit (xlibs) libX11 libICE libSM;
   };
 
-  gnash = assert mesaSupported; import ../applications/video/gnash {
+  gnash = import ../applications/video/gnash {
     inherit fetchurl stdenv SDL SDL_mixer libogg libxml2 libjpeg mesa libpng
             boost freetype agg dbus curl pkgconfig x11 libtool lib libungif
             gettext makeWrapper ming dejagnu python;