diff --git a/lib/systems/examples.nix b/lib/systems/examples.nix
index f3abfe2c621f..80e320406bf4 100644
--- a/lib/systems/examples.nix
+++ b/lib/systems/examples.nix
@@ -11,22 +11,19 @@ rec {
 
   sheevaplug = rec {
     config = "armv5tel-unknown-linux-gnueabi";
-    arch = "armv5tel";
     float = "soft";
     platform = platforms.sheevaplug;
   };
 
   raspberryPi = rec {
     config = "armv6l-unknown-linux-gnueabihf";
-    arch = "armv6l";
     float = "hard";
     fpu = "vfp";
     platform = platforms.raspberrypi;
   };
 
   armv7l-hf-multiplatform = rec {
-    config = "arm-unknown-linux-gnueabihf";
-    arch = "armv7-a";
+    config = "armv7a-unknown-linux-gnueabihf";
     float = "hard";
     fpu = "vfpv3-d16";
     platform = platforms.armv7l-hf-multiplatform;
@@ -34,13 +31,11 @@ rec {
 
   aarch64-multiplatform = rec {
     config = "aarch64-unknown-linux-gnu";
-    arch = "aarch64";
     platform = platforms.aarch64-multiplatform;
   };
 
   aarch64-android-prebuilt = rec {
     config = "aarch64-unknown-linux-android";
-    arch = "aarch64";
     platform = platforms.aarch64-multiplatform;
     useAndroidPrebuilt = true;
   };
@@ -51,7 +46,6 @@ rec {
   };
 
   pogoplug4 = rec {
-    arch = "armv5tel";
     config = "armv5tel-unknown-linux-gnueabi";
     float = "soft";
     platform = platforms.pogoplug4;
@@ -59,7 +53,6 @@ rec {
 
   ben-nanonote = rec {
     config = "mipsel-unknown-linux-uclibc";
-    arch = "mips";
     float = "soft";
     platform = {
       name = "ben_nanonote";
@@ -73,7 +66,6 @@ rec {
 
   fuloongminipc = rec {
     config = "mipsel-unknown-linux-gnu";
-    arch = "mips";
     float = "hard";
     platform = platforms.fuloong2f_n32;
   };
@@ -122,7 +114,6 @@ rec {
   # 32 bit mingw-w64
   mingw32 = {
     config = "i686-pc-mingw32";
-    arch = "x86"; # Irrelevant
     libc = "msvcrt"; # This distinguishes the mingw (non posix) toolchain
     platform = {};
   };
@@ -131,7 +122,6 @@ rec {
   mingwW64 = {
     # That's the triplet they use in the mingw-w64 docs.
     config = "x86_64-pc-mingw32";
-    arch = "x86_64"; # Irrelevant
     libc = "msvcrt"; # This distinguishes the mingw (non posix) toolchain
     platform = {};
   };
diff --git a/pkgs/applications/video/omxplayer/default.nix b/pkgs/applications/video/omxplayer/default.nix
index 825bfe7955a8..520451df400f 100644
--- a/pkgs/applications/video/omxplayer/default.nix
+++ b/pkgs/applications/video/omxplayer/default.nix
@@ -52,7 +52,7 @@ let
         "--cross-prefix=${stdenv.cc.targetPrefix}"
         "--enable-cross-compile"
         "--target_os=linux"
-        "--arch=${hostPlatform.arch}"
+        "--arch=${hostPlatform.parsed.cpu.name}"
         ];
     };
 
diff --git a/pkgs/development/libraries/ffmpeg-full/default.nix b/pkgs/development/libraries/ffmpeg-full/default.nix
index 67e364715f09..f991418ffdab 100644
--- a/pkgs/development/libraries/ffmpeg-full/default.nix
+++ b/pkgs/development/libraries/ffmpeg-full/default.nix
@@ -442,7 +442,7 @@ stdenv.mkDerivation rec {
       "--cross-prefix=${stdenv.cc.targetPrefix}"
       "--enable-cross-compile"
       "--target_os=${hostPlatform.parsed.kernel.name}"
-      "--arch=${hostPlatform.arch}"
+      "--arch=${hostPlatform.parsed.cpu.name}"
     ];
   };
 
diff --git a/pkgs/development/libraries/ffmpeg/generic.nix b/pkgs/development/libraries/ffmpeg/generic.nix
index 4a05eab87bd7..530639d757de 100644
--- a/pkgs/development/libraries/ffmpeg/generic.nix
+++ b/pkgs/development/libraries/ffmpeg/generic.nix
@@ -176,7 +176,7 @@ stdenv.mkDerivation rec {
       "--cross-prefix=${stdenv.cc.targetPrefix}"
       "--enable-cross-compile"
       "--target_os=${hostPlatform.parsed.kernel.name}"
-      "--arch=${hostPlatform.arch}"
+      "--arch=${hostPlatform.parsed.cpu.name}"
     ];
   };
 
diff --git a/pkgs/development/libraries/fontconfig/2.10.nix b/pkgs/development/libraries/fontconfig/2.10.nix
index 3f3c04b15a30..5fb0ea4429e7 100644
--- a/pkgs/development/libraries/fontconfig/2.10.nix
+++ b/pkgs/development/libraries/fontconfig/2.10.nix
@@ -24,7 +24,9 @@ stdenv.mkDerivation rec {
   ];
 
   # We should find a better way to access the arch reliably.
-  crossArch = hostPlatform.arch or null;
+  crossArch = if stdenv.hostPlatform != stdenv.buildPlatform
+    then hostPlatform.parsed.cpu.name
+    else null;
 
   preConfigure = ''
     if test -n "$crossConfig"; then
diff --git a/pkgs/development/libraries/fontconfig/default.nix b/pkgs/development/libraries/fontconfig/default.nix
index 9c4116c8f0ba..ce41f1ac7ebc 100644
--- a/pkgs/development/libraries/fontconfig/default.nix
+++ b/pkgs/development/libraries/fontconfig/default.nix
@@ -56,7 +56,9 @@ stdenv.mkDerivation rec {
   ];
 
   # We should find a better way to access the arch reliably.
-  crossArch = hostPlatform.arch or null;
+  crossArch = if stdenv.hostPlatform != stdenv.buildPlatform
+    then hostPlatform.parsed.cpu.name
+    else null;
 
   preConfigure = ''
     if test -n "$crossConfig"; then
diff --git a/pkgs/development/libraries/libav/default.nix b/pkgs/development/libraries/libav/default.nix
index a069894f6c8c..1b52d18fd6b1 100644
--- a/pkgs/development/libraries/libav/default.nix
+++ b/pkgs/development/libraries/libav/default.nix
@@ -113,7 +113,7 @@ let
         "--cross-prefix=${stdenv.cc.targetPrefix}"
         "--enable-cross-compile"
         "--target_os=linux"
-        "--arch=${hostPlatform.arch}"
+        "--arch=${hostPlatform.parsed.cpu.name}"
         ];
     };