diff --git a/.gitignore b/.gitignore
index 4ba9226..22538ad 100644
--- a/.gitignore
+++ b/.gitignore
@@ -515,3 +515,4 @@ firefox-3.6.4.source.tar.bz2
 /firefox-langpacks-101.0-20220530.tar.xz
 /firefox-101.0.1.source.tar.xz
 /firefox-langpacks-101.0.1-20220609.tar.xz
+/wasi-sysroot-16.0.tar.gz
diff --git a/firefox-mozconfig b/firefox-mozconfig
index 90dfccf..469d5c1 100644
--- a/firefox-mozconfig
+++ b/firefox-mozconfig
@@ -15,8 +15,6 @@ ac_add_options --allow-addon-sideload
 ac_add_options --with-system-fdk-aac
 ac_add_options --enable-js-shell
 ac_add_options --with-unsigned-addon-scopes=app,system
-ac_add_options --without-sysroot
-ac_add_options --without-wasm-sandboxed-libraries
 
 export BUILD_OFFICIAL=1
 export MOZILLA_OFFICIAL=1
diff --git a/firefox.spec b/firefox.spec
index 92efbb1..18dda69 100644
--- a/firefox.spec
+++ b/firefox.spec
@@ -1,6 +1,6 @@
 # Produce a build suitable for release, i.e. use PGO/LTO. You can turn it off
 # when building locally to reduce build time.
-%global release_build     1
+%global release_build     0
 
 # Run Mozilla test suite as a part of compile rpm section. Turn off when
 # building locally and don't want to spend 24 hours waiting for results.
@@ -171,6 +171,7 @@ Source0:        https://archive.mozilla.org/pub/firefox/releases/%{version}%{?pr
 Source1:        firefox-langpacks-%{version}%{?pre_version}-20220609.tar.xz
 %endif
 Source2:        cbindgen-vendor.tar.xz
+Source3:        https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-16/wasi-sysroot-16.0.tar.gz
 Source10:       firefox-mozconfig
 Source12:       firefox-redhat-default-prefs.js
 Source20:       firefox.desktop
@@ -317,9 +318,7 @@ BuildRequires:  llvm
 BuildRequires:  llvm-devel
 BuildRequires:  clang
 BuildRequires:  clang-libs
-%if %{build_with_clang}
 BuildRequires:  lld
-%endif
 
 BuildRequires:  pipewire-devel
 
@@ -647,6 +646,10 @@ echo "ac_add_options --with-google-safebrowsing-api-keyfile=`pwd`/google-api-key
 
 echo 'export NODEJS="%{_buildrootdir}/bin/node-stdout-nonblocking-wrapper"' >> .mozconfig
 
+# Prepare wasi sdk:
+%{__tar} xf %{SOURCE3}
+echo "ac_add_options --with-wasi-sysroot=`pwd`/wasi-sysroot" >> .mozconfig
+
 # Remove executable bit to make brp-mangle-shebangs happy.
 chmod -x third_party/rust/itertools/src/lib.rs
 chmod a-x third_party/rust/ash/src/extensions/ext/*.rs
diff --git a/sources b/sources
index e75afbf..f707e70 100644
--- a/sources
+++ b/sources
@@ -2,3 +2,4 @@ SHA512 (mochitest-python.tar.gz) = 18e1aeb475df5fbf1fe3838897d5ac2f3114aa3490307
 SHA512 (firefox-101.0.1.source.tar.xz) = 435a7f6013582933e75c41e554a45beda30b5affd7d3ed7d2876026609ba7f17b2c20b507d9d0c9ce2379e335ec09b021257ba30ac55fabf02dca54b03ea70b4
 SHA512 (firefox-langpacks-101.0.1-20220609.tar.xz) = 54c93a0fbded6a42948fd578e5577987186ca04695f9c0648718780d3a491b540187addf1239b13c53e532052888bd2ed76788a06c3a2422a060fb0da303ec58
 SHA512 (cbindgen-vendor.tar.xz) = d681ca855f3779553b4a452f9dc1e3acea6253b7ef33a65948ab2d32d9848e8c06f0b3f3504ef237d6b9adb4813bdad990f7a79fa9f89333ce0d4e8da7e12d94
+SHA512 (wasi-sysroot-16.0.tar.gz) = 21aa04749273aef09523aeb4a38430d273b50276b960f9efed8466d19950124752ab4db79be1b5a54fa93d10ad4ceb7dff258f9f4cf5c7bdd59b3e9d0d7bc0a1