diff --git a/.github/scripts/build.sh b/.github/scripts/build.sh
deleted file mode 100755
index 104461d7cf..0000000000
--- a/.github/scripts/build.sh
+++ /dev/null
@@ -1,65 +0,0 @@
-#! /usr/bin/env sh
-
-set -ex
-
-echo "Building..."
-
-sudo apt-get -qq update
-sudo apt-get install -y cmake pkg-config libgnutls28-dev libgmp-dev libffi-dev libicu-dev \
-     libxml2-dev libxslt1-dev libssl-dev libavahi-client-dev zlib1g-dev gnutls-bin \
-     libcairo2-dev
-
-if [ $LIBRARY_COMBO = 'gnu-gnu-gnu' ];
-then
-  if [ $CC = 'gcc' ];
-  then
-    sudo apt-get install -y gobjc;
-  fi;
-  sudo apt-get install -y libobjc-10-dev libblocksruntime-dev;
-else
-  curl -s -o - https://apt.llvm.org/llvm-snapshot.gpg.key|sudo apt-key add -;
-  sudo apt-add-repository "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-9 main" && sudo apt-get update -qq;
-  sudo apt-get install -y clang-9 libkqueue-dev libpthread-workqueue-dev;
-#  sudo update-alternatives   --install /usr/bin/clang   clang   /usr/bin/clang-9   10 \
-#                             --slave   /usr/bin/clang++ clang++ /usr/bin/clang++-9;
-  export PATH=$(echo "$PATH" | sed -e 's/:\/usr\/local\/clang-7.0.0\/bin//');
-  if [ "$RUNTIME_VERSION" = "gnustep-2.0" ];
-  then
-     sudo update-alternatives --install "/usr/bin/ld" "ld" "/usr/bin/ld.gold" 10;
-  fi;
-fi;
-
-if [ $LIBRARY_COMBO = 'ng-gnu-gnu' ];
-then
-  curl -LO https://cmake.org/files/v3.15/cmake-3.15.5-Linux-x86_64.tar.gz;
-  tar xf cmake-3.15.5-Linux-x86_64.tar.gz;
-  mv cmake-3.15.5-Linux-x86_64 $HOME/cmake;
-  export PATH=$HOME/cmake/:$HOME/cmake/bin:$PATH
-fi;
-
-# build dependencies...
-./.github/scripts/dependencies.sh
-
-export LIBRARY_PATH=$HOME/staging/lib:$HOME/staging/lib64:$LIBRARY_PATH;
-export LD_LIBRARY_PATH=$HOME/staging/lib:$HOME/staging/lib64:$LD_LIBRARY_PATH;
-if [ $LIBRARY_COMBO = 'ng-gnu-gnu' ];
-then
-  export CPATH=$HOME/staging/include;
-else
-  export CPATH=/usr/lib/gcc/x86_64-linux-gnu/4.8/include;
-fi;
-export PATH=$HOME/staging/bin:$PATH;
-export GNUSTEP_MAKEFILES=$HOME/staging/share/GNUstep/Makefiles;
-. $HOME/staging/share/GNUstep/Makefiles/GNUstep.sh;
-
-# Build gui
-./configure $BASE_ABI || (cat config.log && false);
-make && make install
-
-# Build back, it's needed by some tests...
-#cd ..
-#git clone https://github.com/gnustep/libs-back.git
-#cd libs-back
-#./configure
-#make && make install
-
diff --git a/.github/scripts/dependencies.sh b/.github/scripts/dependencies.sh
index 0584373809..89323adcd0 100755
--- a/.github/scripts/dependencies.sh
+++ b/.github/scripts/dependencies.sh
@@ -2,72 +2,83 @@
 
 set -ex
 
-DEP_SRC=$HOME/dependency_source/
-DEP_ROOT=$HOME/staging
-
 install_gnustep_make() {
-    cd $DEP_SRC
-    git clone https://github.com/gnustep/tools-make.git
+    echo "::group::GNUstep Make"
+    cd $DEPS_PATH
+    git clone -q -b ${TOOLS_MAKE_BRANCH:-master} https://github.com/gnustep/tools-make.git
     cd tools-make
-    if [ -n "$RUNTIME_VERSION" ]
-    then
-        WITH_RUNTIME_ABI="--with-runtime-abi=${RUNTIME_VERSION}"
-    else
-        WITH_RUNTIME_ABI=""
+    MAKE_OPTS=
+    if [ -n "$HOST" ]; then
+      MAKE_OPTS="$MAKE_OPTS --host=$HOST"
+    fi
+    if [ -n "$RUNTIME_VERSION" ]; then
+      MAKE_OPTS="$MAKE_OPTS --with-runtime-abi=$RUNTIME_VERSION"
     fi
-    ./configure --prefix=$DEP_ROOT --with-library-combo=$LIBRARY_COMBO $WITH_RUNTIME_ABI
+    ./configure --prefix=$INSTALL_PATH --with-library-combo=$LIBRARY_COMBO $MAKE_OPTS || cat config.log
     make install
-    echo Objective-C build flags: `$HOME/staging/bin/gnustep-config --objc-flags`
+
+    echo Objective-C build flags:
+    $INSTALL_PATH/bin/gnustep-config --objc-flags
+    echo "::endgroup::"
 }
 
-install_ng_runtime() {
-    cd $DEP_SRC
-    git clone https://github.com/gnustep/libobjc2.git
+install_libobjc2() {
+    echo "::group::libobjc2"
+    cd $DEPS_PATH
+    git clone -q https://github.com/gnustep/libobjc2.git
     cd libobjc2
-    git submodule init
     git submodule sync
-    git submodule update
-    cd ..
-    mkdir libobjc2/build
-    cd libobjc2/build
-    export CC="clang"
-    export CXX="clang++"
-    export CXXFLAGS="-std=c++11"
-    cmake -DTESTS=off -DCMAKE_BUILD_TYPE=RelWithDebInfo -DGNUSTEP_INSTALL_TYPE=NONE -DCMAKE_INSTALL_PREFIX:PATH=$DEP_ROOT ../
+    git submodule update --init
+    mkdir build
+    cd build
+    cmake \
+      -DTESTS=off \
+      -DCMAKE_BUILD_TYPE=RelWithDebInfo \
+      -DGNUSTEP_INSTALL_TYPE=NONE \
+      -DCMAKE_INSTALL_PREFIX:PATH=$INSTALL_PATH \
+      ../
     make install
+    echo "::endgroup::"
 }
 
 install_libdispatch() {
-    cd $DEP_SRC
+    echo "::group::libdispatch"
+    cd $DEPS_PATH
     # will reference upstream after https://github.com/apple/swift-corelibs-libdispatch/pull/534 is merged
-    git clone -b system-blocksruntime https://github.com/ngrewe/swift-corelibs-libdispatch.git
-    mkdir swift-corelibs-libdispatch/build
-    cd swift-corelibs-libdispatch/build
-    export CC="clang"
-    export CXX="clang++"
-    export LIBRARY_PATH=$DEP_ROOT/lib;
-    export LD_LIBRARY_PATH=$DEP_ROOT/lib:$LD_LIBRARY_PATH;
-    export CPATH=$DEP_ROOT/include;
-    cmake -DBUILD_TESTING=off -DCMAKE_BUILD_TYPE=RelWithDebInfo  -DCMAKE_INSTALL_PREFIX:PATH=$HOME/staging -DINSTALL_PRIVATE_HEADERS=1 -DBlocksRuntime_INCLUDE_DIR=$DEP_ROOT/include -DBlocksRuntime_LIBRARIES=$DEP_ROOT/lib/libobjc.so ../
+    git clone -q -b system-blocksruntime https://github.com/ngrewe/swift-corelibs-libdispatch.git libdispatch
+    mkdir libdispatch/build
+    cd libdispatch/build
+    # -Wno-error=void-pointer-to-int-cast to work around build error in queue.c due to -Werror
+    cmake \
+      -DBUILD_TESTING=off \
+      -DCMAKE_BUILD_TYPE=RelWithDebInfo \
+      -DCMAKE_INSTALL_PREFIX:PATH=$INSTALL_PATH \
+      -DCMAKE_C_FLAGS="-Wno-error=void-pointer-to-int-cast" \
+      -DINSTALL_PRIVATE_HEADERS=1 \
+      -DBlocksRuntime_INCLUDE_DIR=$INSTALL_PATH/include \
+      -DBlocksRuntime_LIBRARIES=$INSTALL_PATH/lib/libobjc.so \
+      ../
     make install
+    echo "::endgroup::"
 }
 
 install_gnustep_base() {
-    export GNUSTEP_MAKEFILES=$HOME/staging/share/GNUstep/Makefiles
-    . $HOME/staging/share/GNUstep/Makefiles/GNUstep.sh
-
-    cd $DEP_SRC
-    git clone https://github.com/gnustep/libs-base.git
+    echo "::group::GNUstep Base"
+    cd $DEPS_PATH
+    . $INSTALL_PATH/share/GNUstep/Makefiles/GNUstep.sh
+    git clone -q -b ${LIBS_BASE_BRANCH:-master} https://github.com/gnustep/libs-base.git
     cd libs-base
     ./configure
     make
     make install
+    echo "::endgroup::"
 }
 
-mkdir -p $DEP_SRC
-if [ "$LIBRARY_COMBO" = 'ng-gnu-gnu' ]
-then
-    install_ng_runtime
+mkdir -p $DEPS_PATH
+
+# Windows MSVC toolchain uses tools-windows-msvc scripts to install non-GNUstep dependencies
+if [ "$LIBRARY_COMBO" = "ng-gnu-gnu" -a "$IS_WINDOWS_MSVC" != "true" ]; then
+    install_libobjc2
     install_libdispatch
 fi
 
diff --git a/.github/scripts/test.sh b/.github/scripts/test.sh
deleted file mode 100755
index 17a04644e5..0000000000
--- a/.github/scripts/test.sh
+++ /dev/null
@@ -1,8 +0,0 @@
-#! /usr/bin/env sh
-
-set -ex
-
-echo "Running unit tests"
-. $HOME/staging/share/GNUstep/Makefiles/GNUstep.sh;
-make check || (cat Tests/tests.log && false);
-
diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 19733316a4..0abb69ec3a 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -1,29 +1,138 @@
-# This is a basic workflow to help you get started with Actions
-
 name: CI
 
-# Controls when the workflow will run
-on: push
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+    inputs:
+      tools_make_branch:
+        description: "tools-make branch"
+        default: "master"
+        required: true
+      libs_base_branch:
+        description: "libs-base branch"
+        default: "master"
+        required: true
+      libs_back_branch:
+        description: "libs-back branch"
+        default: "master"
+        required: true
+
+env:
+  APT_PACKAGES: >-
+    pkg-config
+    libgnutls28-dev
+    libffi-dev
+    libicu-dev
+    libxml2-dev
+    libxslt1-dev
+    libssl-dev
+    libavahi-client-dev
+    zlib1g-dev
+    gnutls-bin
+    libcurl4-gnutls-dev
+    libgmp-dev
+    libcairo2-dev
+
+  # packages for GCC Objective-C runtime
+  APT_PACKAGES_gcc: >-
+    libobjc-10-dev
+    libblocksruntime-dev
+    gobjc
+
+  # packages for libobjc2 / libdispatch
+  APT_PACKAGES_clang: >-
+    libpthread-workqueue-dev
 
-# A workflow run is made up of one or more jobs that can run sequentially or in parallel
 jobs:
-  # This workflow contains a single job called "build"
-  build:
-    # The type of runner that the job will run on
+  ########### Linux ###########
+  linux:
+    name: ${{ matrix.name }}
     runs-on: ubuntu-latest
+    # don't run pull requests from local branches twice
+    if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name != github.repository
+
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - name: Ubuntu x64 GCC
+            library-combo: gnu-gnu-gnu
+            CC: gcc
+            CXX: g++
+
+          - name: Ubuntu x64 Clang gnustep-1.9
+            library-combo: ng-gnu-gnu
+            runtime-version: gnustep-1.9
+            CC: clang
+            CXX: clang++
+
+          - name: Ubuntu x64 Clang gnustep-2.0
+            library-combo: ng-gnu-gnu
+            runtime-version: gnustep-2.0
+            CC: clang
+            CXX: clang++
+
     env:
-      LIBRARY_COMBO: gnu-gnu-gnu
-      CC: gcc
-      
-    # Steps represent a sequence of tasks that will be executed as part of the job
+      SRC_PATH: ${{ github.workspace }}/source
+      DEPS_PATH: ${{ github.workspace }}/dependencies
+      INSTALL_PATH: ${{ github.workspace }}/build
+      CC: ${{ matrix.CC }}
+      CXX: ${{ matrix.CXX }}
+      LIBRARY_COMBO: ${{ matrix.library-combo }}
+      RUNTIME_VERSION: ${{ matrix.runtime-version }}
+
+    defaults:
+      run:
+        working-directory: ${{ env.SRC_PATH }}
+
     steps:
-      # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
+        with:
+          path: ${{ env.SRC_PATH }}
+
+      - name: Install packages
+        run: |
+          sudo apt-get -q -y update
+          sudo apt-get -q -y install $APT_PACKAGES $APT_PACKAGES_${{ matrix.library-combo == 'ng-gnu-gnu' && 'clang' || 'gcc' }}
+
+          # gnustep-2.0 runtime requires ld.gold or lld
+          if [ "$RUNTIME_VERSION" = "gnustep-2.0" ]; then
+            sudo update-alternatives --install "/usr/bin/ld" "ld" "/usr/bin/ld.gold" 10
+          fi
+
+      - name: Install dependencies
+        env:
+          TOOLS_MAKE_BRANCH: ${{github.event.inputs.tools_make_branch}}
+          LIBS_BASE_BRANCH: ${{github.event.inputs.libs_base_branch}}
+        run: ./.github/scripts/dependencies.sh
 
-      # Runs a single command using the runners shell
       - name: Build source
-        run: ./.github/scripts/build.sh
+        run: |
+          . $INSTALL_PATH/share/GNUstep/Makefiles/GNUstep.sh
+          ./configure
+          make && make install
+
+### Building libs-back is disabled due to various test failures. Re-enable when fixed.
+#      - name: Build libs-back # required by some tests
+#        working-directory: ${{env.DEPS_PATH}}
+#        run: |
+#          . $INSTALL_PATH/share/GNUstep/Makefiles/GNUstep.sh
+#          git clone -q -b ${LIBS_BACK_BRANCH:-master} https://github.com/gnustep/libs-back.git
+#          cd libs-back
+#          ./configure
+#          make && make install
 
-      # Runs a single command using the runners shell
       - name: Run tests
-        run: ./.github/scripts/test.sh
+        run: |
+          . $INSTALL_PATH/share/GNUstep/Makefiles/GNUstep.sh
+          make check
+
+      - name: Upload logs
+        uses: actions/upload-artifact@v3
+        if: always()
+        with:
+          name: Logs - ${{ matrix.name }}
+          path: |
+            ${{ env.SRC_PATH }}/config.log
+            ${{ env.SRC_PATH }}/Tests/tests.log