diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0cfce36..fe3f7ef 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -21,31 +21,30 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        otp: ['21.3', '24.3', '25']
-        rebar: ['rebar3']
-        include:
-        - otp: '21.3'
-          os: ubuntu-20.04
-        - otp: '24.3'
-          os: ubuntu-20.04
-        - otp: '25'
-          os: ubuntu-20.04
-    runs-on: ${{ matrix.os }}
+        otp: ['21.0', '21.3', '24.3', '25']
+    runs-on: ubuntu-latest
     container:
       image: erlang:${{ matrix.otp }}
 
     steps:
 
     - name: Checkout ejabberd
-      uses: actions/checkout@v2
+      uses: actions/checkout@v3
       with:
         repository: processone/ejabberd
 
     - name: Checkout ejabberd-contrib
-      uses: actions/checkout@v2
+      uses: actions/checkout@v3
       with:
         path: .ejabberd-modules/sources/ejabberd-contrib
 
+    - name: Get a compatible Rebar3
+      if: matrix.otp <= '21.3'
+      run: |
+        rm rebar3
+        wget https://github.com/processone/ejabberd/raw/21.12/rebar3
+        chmod +x rebar3
+
     - name: Prepare libraries
       run: |
         apt-get -qq update
@@ -58,6 +57,7 @@ jobs:
       run: |
         echo '{xref_ignores, [{eldap_filter_yecc, return_error, 2},
                               {fusco_lib, split_credentials, 1},
+                              {http_uri, encode, 1},
                               {http_uri, decode, 1}
                              ]}.' >>rebar.config
         echo '{xref_checks, [deprecated_function_calls, deprecated_functions,
@@ -76,16 +76,13 @@ jobs:
       uses: actions/cache@v3
       with:
         path: |
-          deps/
-          dialyzer/
-          ebin/
           ~/.cache/rebar3/
-        key: ${{matrix.otp}}-${{matrix.rebar}}-${{hashFiles('rebar.config')}}
+        key: ${{matrix.otp}}-${{hashFiles('rebar.config')}}
 
     - name: Compile
       run: |
         ./autogen.sh
-        ./configure --with-rebar=`which rebar3` \
+        ./configure --with-rebar=./rebar3 \
                     --prefix=/tmp/ejabberd \
                     --enable-all \
                     --disable-elixir \