diff --git a/default.nix b/default.nix
index f624865f9..66112032b 100644
--- a/default.nix
+++ b/default.nix
@@ -113,6 +113,8 @@ let iosSupport = system == "x86_64-darwin";
 
     inherit (nixpkgs) lib fetchurl fetchgit fetchgitPrivate fetchFromGitHub fetchFromBitbucket;
 
+    wasmCross = nixpkgs.hackGet ./wasm-cross;
+    webGhcSrc = (import (wasmCross + /webghc.nix) { inherit fetchgit; }).ghc865SplicesSrc;
     nixpkgsCross = {
       android = lib.mapAttrs (_: args: nixpkgsFunc (nixpkgsArgs // args)) rec {
         aarch64 = {
@@ -149,6 +151,9 @@ let iosSupport = system == "x86_64-darwin";
       ghcjs = nixpkgsFunc (nixpkgsArgs // {
         crossSystem = lib.systems.examples.ghcjs;
       });
+      wasm = nixpkgsFunc (nixpkgsArgs //
+        (import wasmCross { inherit nixpkgsFunc; }).nixpkgsCrossArgs webGhcSrc "8.6.5"
+      );
     };
 
     haskellLib = nixpkgs.haskell.lib;
@@ -205,6 +210,14 @@ let iosSupport = system == "x86_64-darwin";
     overrides = nixpkgsCross.ghcjs.haskell.overlays.combined;
   };
 
+  wasm = ghcWasm32-8_6;
+  ghcWasm32-8_6 = makeRecursivelyOverridableBHPToo ((makeRecursivelyOverridable (nixpkgsCross.wasm.haskell.packages.ghcWasm.override (old: {
+    # Due to the splices changes the parallel build fails while building the libraries
+    ghc = old.ghc.overrideAttrs (drv: { enableParallelBuilding = false; });
+  }))).override {
+    overrides = nixpkgsCross.wasm.haskell.overlays.combined;
+  });
+
   ghc = ghc8_6;
   ghcHEAD = (makeRecursivelyOverridable nixpkgs.haskell.packages.ghcHEAD).override {
     overrides = nixpkgs.haskell.overlays.combined;
@@ -299,6 +312,8 @@ in let this = rec {
           iosAarch32
           iosAarch64
           iosWithHaskellPackages
+          wasm
+          wasmCross
           ;
 
   # Back compat
diff --git a/haskell-overlays/default.nix b/haskell-overlays/default.nix
index fd277885a..454167ce8 100644
--- a/haskell-overlays/default.nix
+++ b/haskell-overlays/default.nix
@@ -10,6 +10,7 @@
 
 let
   inherit (nixpkgs.buildPackages) thunkSet runCommand fetchgit fetchFromGitHub fetchFromBitbucket;
+  inherit (nixpkgs) hackGet;
 in
 
 rec {
@@ -53,6 +54,7 @@ rec {
 
     (optionalExtension (nixpkgs.stdenv.hostPlatform.useAndroidPrebuilt or false) android)
     (optionalExtension (nixpkgs.stdenv.hostPlatform.isiOS or false) ios)
+    (optionalExtension (nixpkgs.stdenv.hostPlatform.isWasm or false) wasm)
 
     user-custom-post
   ] self super;
@@ -85,7 +87,7 @@ rec {
 
   reflexPackages = import ./reflex-packages {
     inherit
-      haskellLib lib nixpkgs thunkSet fetchFromGitHub fetchFromBitbucket
+      haskellLib lib nixpkgs thunkSet fetchFromGitHub fetchFromBitbucket hackGet
       useFastWeak useReflexOptimizer enableTraceReflexEvents enableLibraryProfiling __useTemplateHaskell
       ;
   };
@@ -156,6 +158,8 @@ rec {
     inherit thunkSet;
   };
 
+  wasm = import ./wasm;
+
   user-custom-pre = foldExtensions haskellOverlaysPre;
   user-custom-post = foldExtensions haskellOverlaysPost;
 }
diff --git a/haskell-overlays/reflex-packages/default.nix b/haskell-overlays/reflex-packages/default.nix
index 7662e2366..5815ed081 100644
--- a/haskell-overlays/reflex-packages/default.nix
+++ b/haskell-overlays/reflex-packages/default.nix
@@ -1,6 +1,6 @@
 { haskellLib
 , lib, nixpkgs
-, thunkSet, fetchFromGitHub, fetchFromBitbucket
+, thunkSet, fetchFromGitHub, fetchFromBitbucket, hackGet
 , useFastWeak, useReflexOptimizer, enableTraceReflexEvents, enableLibraryProfiling, __useTemplateHaskell
 }:
 
@@ -13,6 +13,7 @@ let
   reflexDomRepo = self._dep.reflex-dom;
   jsaddleSrc = self._dep.jsaddle;
   gargoylePkgs = self.callPackage self._dep.gargoyle self;
+  wasmCross = hackGet ../../wasm-cross;
 
   reflexOptimizerFlag = lib.optional (useReflexOptimizer && (self.ghc.cross or null) == null) "-fuse-reflex-optimizer";
   useTemplateHaskellFlag = lib.optional (!__useTemplateHaskell) "-f-use-template-haskell";
@@ -86,8 +87,11 @@ in
     ])) {})
     (drv: {
       # Hack until https://github.com/NixOS/cabal2nix/pull/432 lands
-      libraryHaskellDepends = (drv.libraryHaskellDepends or []) ++ stdenv.lib.optionals (with stdenv.hostPlatform; isAndroid && is32bit) [
+      libraryHaskellDepends = (drv.libraryHaskellDepends or [])
+        ++ stdenv.lib.optionals (with stdenv.hostPlatform; isAndroid && is32bit) [
         self.android-activity
+      ] ++ stdenv.lib.optionals (with stdenv.hostPlatform; isWasm && is32bit) [
+        self.jsaddle-wasm
       ];
     });
 
@@ -129,6 +133,7 @@ in
   jsaddle-warp = dontCheck (self.callCabal2nix "jsaddle-warp" (jsaddleSrc + /jsaddle-warp) {});
 
   jsaddle-dom = self.callCabal2nix "jsaddle-dom" self._dep.jsaddle-dom {};
+  jsaddle-wasm = self.callCabal2nix "jsaddle-wasm" (hackGet (wasmCross + /jsaddle-wasm)) {};
   ghcjs-dom = self.callCabal2nix "ghcjs-dom" (self._dep.ghcjs-dom + "/ghcjs-dom") {};
   ghcjs-dom-jsaddle = self.callCabal2nix "ghcjs-dom-jsaddle" (self._dep.ghcjs-dom + "/ghcjs-dom-jsaddle") {};
   ghcjs-dom-jsffi = self.callCabal2nix "ghcjs-dom-jsffi" (self._dep.ghcjs-dom + "/ghcjs-dom-jsffi") {};
diff --git a/haskell-overlays/reflex-packages/dep/reflex-dom/github.json b/haskell-overlays/reflex-packages/dep/reflex-dom/github.json
index eadc5c799..1813952d8 100644
--- a/haskell-overlays/reflex-packages/dep/reflex-dom/github.json
+++ b/haskell-overlays/reflex-packages/dep/reflex-dom/github.json
@@ -1,7 +1,7 @@
 {
   "owner": "reflex-frp",
   "repo": "reflex-dom",
-  "branch": "master",
-  "rev": "94c26076a71f229b5bd27128cf6fc0dbcba011ac",
-  "sha256": "00sx5x51jv1j24qlhrbp5sqnqcyz1iy2sgjap0y97c4dkzxi3wd3"
+  "branch": "develop",
+  "rev": "e2b846037badee035d0c466173badd1c4c474d5a",
+  "sha256": "12vj25zzg2xr6mvyw83skr24y30swmg79kmg7lizy3klwpv5dysc"
 }
diff --git a/haskell-overlays/wasm/default.nix b/haskell-overlays/wasm/default.nix
new file mode 100644
index 000000000..843f530ab
--- /dev/null
+++ b/haskell-overlays/wasm/default.nix
@@ -0,0 +1,16 @@
+self: super: {
+  jsaddle-warp = null;
+  jsaddle-webkitgtk = null;
+  jsaddle-webkit2gtk = null;
+  jsaddle-wkwebview = null;
+  mkDerivation = args: super.mkDerivation (args // {
+    dontStrip = true;
+    enableSharedExecutables = false;
+    enableSharedLibraries = false;
+    enableDeadCodeElimination = false;
+    doHaddock = false;
+    doCheck = false;
+    enableLibraryProfiling = false;
+  });
+}
+
diff --git a/nixpkgs/github.json b/nixpkgs/github.json
index f38046a6f..3e03f244b 100644
--- a/nixpkgs/github.json
+++ b/nixpkgs/github.json
@@ -1,7 +1,7 @@
 {
-  "owner": "nixos",
+  "owner": "WebGHC",
   "repo": "nixpkgs",
-  "branch": "release-19.09",
-  "rev": "49550f29cd9d6ed27f4a76ba3c3fe30edf882eb7",
-  "sha256": "003fpkrcc5mw33q670q4z865zpr430cllbxhyzj8k9p4hbc8yqda"
+  "branch": "wasm-r-p-1909-integ",
+  "rev": "423fa4adb6276298cde0c12205efeb7bf1cbe805",
+  "sha256": "0ssvc5j0p7nip0qsrdbfgc6wihzwyxa23hbr80dmjbfizywz7nzg"
 }
diff --git a/wasm-cross/default.nix b/wasm-cross/default.nix
new file mode 100644
index 000000000..0cf822e33
--- /dev/null
+++ b/wasm-cross/default.nix
@@ -0,0 +1,8 @@
+# DO NOT HAND-EDIT THIS FILE
+let fetch = { private ? false, fetchSubmodules ? false, owner, repo, rev, sha256, ... }:
+  if !fetchSubmodules && !private then builtins.fetchTarball {
+    url = "https://github.com/${owner}/${repo}/archive/${rev}.tar.gz"; inherit sha256;
+  } else (import <nixpkgs> {}).fetchFromGitHub {
+    inherit owner repo rev sha256 fetchSubmodules private;
+  };
+in import (fetch (builtins.fromJSON (builtins.readFile ./github.json)))
diff --git a/wasm-cross/github.json b/wasm-cross/github.json
new file mode 100644
index 000000000..cc70cfe4b
--- /dev/null
+++ b/wasm-cross/github.json
@@ -0,0 +1,8 @@
+{
+  "owner": "WebGHC",
+  "repo": "wasm-cross",
+  "branch": "reflex-platform-integ",
+  "private": false,
+  "rev": "98dbc945147ed646724682a2a4f470bc592a5501",
+  "sha256": "1vnxmxx262h6r0lslidd0fnnrsjz88jfx1dj7v66vl0pjdz7icb4"
+}