diff --git a/pkgs/os-specific/linux/kernel-headers/builder.sh b/pkgs/os-specific/linux/kernel-headers/builder.sh
index bf6950273990..efab999fe3b2 100644
--- a/pkgs/os-specific/linux/kernel-headers/builder.sh
+++ b/pkgs/os-specific/linux/kernel-headers/builder.sh
@@ -12,13 +12,6 @@ installPhase() {
     mkdir $out
     mkdir $out/include
     cp -prvd include/linux include/asm-generic $out/include
-    if test $system = "i686-linux"; then
-        platform=i386
-    elif test $system = "x86_64-linux"; then
-        platform=x86_64
-    elif test $system = "powerpc-linux"; then
-        platform=ppw
-    fi
     cp -prvd include/asm-$platform $out/include
     ln -s asm-$platform $out/include/asm
     echo -n > $out/include/linux/autoconf.h
diff --git a/pkgs/os-specific/linux/kernel-headers/default.nix b/pkgs/os-specific/linux/kernel-headers/default.nix
index 73311a409208..944ec2a21cba 100644
--- a/pkgs/os-specific/linux/kernel-headers/default.nix
+++ b/pkgs/os-specific/linux/kernel-headers/default.nix
@@ -9,4 +9,10 @@ stdenv.mkDerivation {
     url = ftp://ftp.nl.kernel.org/pub/linux/kernel/v2.6/linux-2.6.18.1.tar.bz2;
     md5 = "38f00633b02f07819d17bcd87d03eb3a";
   };
+
+  platform = 
+    if stdenv.system == "i686-linux" then "i386" else
+    if stdenv.system == "x86_64-linux" then "x86_64" else
+    if stdenv.system == "powerpc-linux" then "ppc" else
+    abort "don't know what the kernel include directory is called for this platform";
 }