diff --git a/.github/workflows/build-binaries.yml b/.github/workflows/build-binaries.yml
index 60140446a..4ae2bd575 100644
--- a/.github/workflows/build-binaries.yml
+++ b/.github/workflows/build-binaries.yml
@@ -37,13 +37,9 @@ jobs:
         uses: actions/checkout@v2
         with:
           repository: AdaCore/gprbuild
-          path: gprbuild
-          fetch-depth: 0  # To be able do `git revert`
-      - name: Revert a libgpr patch (MacOS X only)
-        # The latest libgpr doesn't support GNAT CE 2020, but on MacOS X we
-        # don't have GNAT CE 2021. Let's revert this commit for now.
-        if: ${{ runner.os == 'macOS' }}
-        run: git -C gprbuild revert --no-edit 3341766255bf5ab90fe05a8e162894b7830adca6
+          # `gprbuild` directory raises a conflict in alr:
+          # https://github.com/alire-project/alire/issues/864
+          path: gprbuild_
       - name: Get gnatcoll core
         uses: actions/checkout@v2
         with:
@@ -66,19 +62,12 @@ jobs:
       - uses: actions/cache@v2
         with:
           path: ./cached_gnat
-          key: ${{ runner.os }}-gnat-ce-2021
-      - name: Get GNAT Community 2021 toolchain
-        if: ${{ runner.os != 'macOS' }}
-        uses: ada-actions/toolchain@ce2021
+          key: ${{ runner.os }}-alire-2021
+      - name: Get GNAT toolchain with alire
+        uses: alire-project/setup-alire@v1
         with:
-          distrib: community
-          install_dir: ./cached_gnat
-      - name: Get GNAT Community 2020 toolchain
-        if: ${{ runner.os == 'macOS' }}
-        uses: ada-actions/toolchain@ce2020
-        with:
-          distrib: community
-          install_dir: ./cached_gnat
+          toolchain: gnat_native^11 gprbuild^21
+          toolchain_dir: ./cached_gnat
       - name: Setup Python 3.8
         uses: actions/setup-python@v2
         with:
diff --git a/utils/gh-build-binaries.sh b/utils/gh-build-binaries.sh
index 34858bb35..a43f86bf1 100755
--- a/utils/gh-build-binaries.sh
+++ b/utils/gh-build-binaries.sh
@@ -12,6 +12,9 @@ export GPR_PROJECT_PATH=$prefix/share/gpr
 export CPATH=/usr/local/include:/mingw64/include
 export LIBRARY_PATH=/usr/local/lib:/mingw64/lib
 export DYLD_LIBRARY_PATH=/usr/local/lib
+export PATH=`ls -d $PWD/cached_gnat/*/bin |tr '\n' ':'`$PATH
+echo PATH=$PATH
+
 if [ $RUNNER_OS = Linux ]; then
    LIBRARY_TYPES="relocatable,static"
 else
@@ -20,11 +23,14 @@ fi
 pip install -r langkit/REQUIREMENTS.dev
 pip install jsonschema
 pip install langkit/
-# gnat-ce installation is cached, so gnatcoll/gpr could be uninstalled already
-gprinstall --uninstall gnatcoll || true
-gprinstall --uninstall gpr      || true
 
-make -C gprbuild prefix=$prefix BUILD=${DEBUG:-production} GPRBUILD_OPTIONS="-cargs:C -Dst_mtim=st_mtimespec -gargs" libgpr.build.{shared,static} libgpr.install.{shared,static}
+alr --non-interactive get xmlada
+cd xmlada*
+./configure --prefix=$prefix ${DEBUG:+--enable-build=Debug}
+make all install
+cd ..
+
+make -C gprbuild_ prefix=$prefix BUILD=${DEBUG:-production} GPRBUILD_OPTIONS="-cargs:C -Dst_mtim=st_mtimespec -gargs" libgpr.build.{shared,static} libgpr.install.{shared,static}
 BUILD=`echo $DEBUG| tr [a-z] [A-Z]`  # Convert to uppercase
 make -C gnatcoll-core prefix=$prefix BUILD=${BUILD:-PROD} LIBRARY_TYPES="${LIBRARY_TYPES/,/ }" build install
 python gnatcoll-bindings/iconv/setup.py build ${DEBUG:+--debug} -j0 --prefix=$prefix --library-types=$LIBRARY_TYPES
@@ -37,12 +43,14 @@ langkit/manage.py build-langkit-support --library-types $LIBRARY_TYPES
 langkit/manage.py install-langkit-support $prefix --library-types $LIBRARY_TYPES
 
 BUILD=${DEBUG:+dev}  # Convert debug to dev
+
 # Build libadalang static library
 ./manage.py generate
 ./manage.py build --library-types=static --build-mode ${BUILD:-prod}
 ./manage.py install --library-types=static --build-mode ${BUILD:-prod} $prefix
 gprinstall --uninstall --prefix=$prefix mains.gpr
 tar czf libadalang-$RUNNER_OS-`basename $GITHUB_REF`${DEBUG:+-dbg}-static.tar.gz -C $prefix .
+
 # Build libadalang relocatable library
 if [ "$LIBRARY_TYPES" != static ]; then
   gprinstall --uninstall --prefix=$prefix libadalang.gpr