diff --git a/lib/systems/for-meta.nix b/lib/systems/for-meta.nix
index fa713b1e6136..63f24b465355 100644
--- a/lib/systems/for-meta.nix
+++ b/lib/systems/for-meta.nix
@@ -4,8 +4,8 @@ let
   inherit (lib.systems.inspect) patterns;
 
 in rec {
-  inherit (lib.systems.doubles) all mesaPlatforms;
-  none = [];
+  all     = [ {} ]; # `{}` matches anything
+  none    = [];
 
   arm     = [ patterns.isArm ];
   aarch64 = [ patterns.isAarch64 ];
@@ -24,4 +24,7 @@ in rec {
   netbsd  = [ patterns.isNetBSD ];
   openbsd = [ patterns.isOpenBSD ];
   unix    = patterns.isUnix; # Actually a list
+  windows = [ patterns.isWindows ];
+
+  inherit (lib.systems.doubles) mesaPlatforms;
 }
diff --git a/pkgs/development/haskell-modules/generic-builder.nix b/pkgs/development/haskell-modules/generic-builder.nix
index 1a788ae642ea..3cdf2e2252b2 100644
--- a/pkgs/development/haskell-modules/generic-builder.nix
+++ b/pkgs/development/haskell-modules/generic-builder.nix
@@ -34,8 +34,8 @@ in
 , enableStaticLibraries ? true
 , extraLibraries ? [], librarySystemDepends ? [], executableSystemDepends ? []
 , homepage ? "http://hackage.haskell.org/package/${pname}"
-, platforms ? ghc.meta.platforms
-, hydraPlatforms ? platforms
+, platforms ? with stdenv.lib.platforms; unix ++ windows # GHC can cross-compile
+, hydraPlatforms ? null
 , hyperlinkSource ? true
 , isExecutable ? false, isLibrary ? !isExecutable
 , jailbreak ? false
@@ -404,7 +404,7 @@ stdenv.mkDerivation ({
          // optionalAttrs broken               { inherit broken; }
          // optionalAttrs (description != "")  { inherit description; }
          // optionalAttrs (maintainers != [])  { inherit maintainers; }
-         // optionalAttrs (hydraPlatforms != platforms) { inherit hydraPlatforms; }
+         // optionalAttrs (hydraPlatforms != null) { inherit hydraPlatforms; }
          ;
 
 }
diff --git a/pkgs/development/libraries/libatomic_ops/default.nix b/pkgs/development/libraries/libatomic_ops/default.nix
index fe4cd3ca0a97..04cf1c1e696e 100644
--- a/pkgs/development/libraries/libatomic_ops/default.nix
+++ b/pkgs/development/libraries/libatomic_ops/default.nix
@@ -28,6 +28,6 @@ stdenv.mkDerivation rec {
     description = ''A library for semi-portable access to hardware-provided atomic memory update operations'';
     license = stdenv.lib.licenses.gpl2Plus ;
     maintainers = [stdenv.lib.maintainers.raskin];
-    platforms = stdenv.lib.platforms.unix;
+    platforms = with stdenv.lib.platforms; unix ++ windows;
   };
 }