diff --git a/.github/workflows/checks.yml b/.github/workflows/checks.yml
index 15416b05..0cf7af21 100644
--- a/.github/workflows/checks.yml
+++ b/.github/workflows/checks.yml
@@ -15,8 +15,8 @@ jobs:
       ACTIONS_ALLOW_UNSECURE_COMMANDS: true
     strategy:
       matrix:
-        elixir: ['1.12.3']
-        erlang: ['24.3']
+        elixir: ['1.12']
+        otp: ['24.3']
 
     steps:
         - name: Cancel previous runs
@@ -31,7 +31,7 @@ jobs:
           uses: actions/setup-elixir@v1
           with:
             elixir-version: ${{matrix.elixir}} # Define the elixir version [required]
-            otp-version: ${{matrix.erlang}} # Define the OTP version [required]
+            otp-version: ${{matrix.otp}} # Define the OTP version [required]
             experimental-otp: true # More info https://github.com/actions/setup-elixir/issues/31
 
         - name: Retrieve Cached Dependencies
@@ -64,8 +64,8 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        elixir: ['1.12.3']
-        erlang: ['24.3']
+        elixir: ['1.12']
+        otp: ['24.3']
 
     steps:
       - name: Cancel Previous Runs
@@ -82,7 +82,7 @@ jobs:
         uses: actions/setup-elixir@v1
         with:
           elixir-version: ${{matrix.elixir}} # Define the elixir version [required]
-          otp-version: ${{matrix.erlang}} # Define the OTP version [required]
+          otp-version: ${{matrix.otp}} # Define the OTP version [required]
           experimental-otp: true # More info https://github.com/actions/setup-elixir/issues/31
 
       - name: Retrieve Cached Dependencies
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index cc46392b..14e57e72 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -14,8 +14,13 @@ jobs:
       MIX_ENV: test
     strategy:
       matrix:
-        elixir: ['1.12.3']
-        erlang: ['24.3']
+        pair:
+          - elixir: 1.13
+            otp: 24.3
+          - elixir: 1.11
+            otp: 21.3
+          - elixir: 1.6
+            otp: 20.3
 
     steps:
       - name: Cancel previous runs
@@ -27,8 +32,8 @@ jobs:
       - name: Setup elixir & erlang enviroment
         uses: actions/setup-elixir@v1
         with:
-          elixir-version: ${{matrix.elixir}} # Define the elixir version [required]
-          otp-version: ${{matrix.erlang}} # Define the OTP version [required]
+          elixir-version: ${{matrix.pair.elixir}} # Define the elixir version [required]
+          otp-version: ${{matrix.pair.otp}} # Define the OTP version [required]
           experimental-otp: true # More info https://github.com/actions/setup-elixir/issues/31
 
       - name: Retrieve Mix Dependencies Cache
@@ -36,14 +41,14 @@ jobs:
         id: mix-cache # id to use in retrieve action
         with:
           path: deps
-          key: ${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}-mix-${{ hashFiles(format('{0}{1}', github.workspace, '/mix.lock')) }}
+          key: ${{ runner.os }}-${{ matrix.pair.otp }}-${{ matrix.pair.elixir }}-mix-${{ hashFiles(format('{0}{1}', github.workspace, '/mix.lock')) }}
 
       - name: Retrieve Mix Dependencies Compilation Cache
         uses: actions/cache@v2
         id: mix-deps-compile-cache # id to use in retrieve action
         with:
           path: _build
-          key: ${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}-mix-deps-compile-${{ hashFiles(format('{0}{1}', github.workspace, '/mix.lock')) }}
+          key: ${{ runner.os }}-${{ matrix.pair.otp }}-${{ matrix.pair.elixir }}-mix-deps-compile-${{ hashFiles(format('{0}{1}', github.workspace, '/mix.lock')) }}
       - name: Install Mix Dependencies
         if: steps.mix-cache.outputs.cache-hit != 'true'
         run: |
@@ -66,17 +71,21 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        include:
-          - elixir: 1.12.3
-            erlang: 24.3
+        pair:
+          - elixir: 1.13
+            otp: 24.3
+          - elixir: 1.11
+            otp: 21.3
+          - elixir: 1.6
+            otp: 20.3
 
     steps:
       - uses: actions/checkout@v2
       - name: Setup elixir & erlang enviroment
         uses: actions/setup-elixir@v1
         with:
-          elixir-version: ${{matrix.elixir}} # Define the elixir version [required]
-          otp-version: ${{matrix.erlang}} # Define the OTP version [required]
+          elixir-version: ${{matrix.pair.elixir}} # Define the elixir version [required]
+          otp-version: ${{matrix.pair.otp}} # Define the OTP version [required]
           experimental-otp: true # More info https://github.com/actions/setup-elixir/issues/31
 
       - name: Retrieve Mix Dependencies Cache
@@ -84,14 +93,14 @@ jobs:
         id: mix-cache # id to use in retrieve action
         with:
           path: deps
-          key: ${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}-mix-${{ hashFiles(format('{0}{1}', github.workspace, '/mix.lock')) }}
+          key: ${{ runner.os }}-${{ matrix.pair.otp }}-${{ matrix.pair.elixir }}-mix-${{ hashFiles(format('{0}{1}', github.workspace, '/mix.lock')) }}
 
       - name: Retrieve Mix Dependencies Compilation Cache
         uses: actions/cache@v2
         id: mix-deps-compile-cache # id to use in retrieve action
         with:
           path: _build
-          key: ${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}-mix-deps-compile-${{ hashFiles(format('{0}{1}', github.workspace, '/mix.lock')) }}
+          key: ${{ runner.os }}-${{ matrix.pair.otp }}-${{ matrix.pair.elixir }}-mix-deps-compile-${{ hashFiles(format('{0}{1}', github.workspace, '/mix.lock')) }}
 
       - name: Docker-compose up
         run: ./scripts/docker_up.sh
diff --git a/test/socket_test.exs b/test/socket_test.exs
index 47a69fe2..dab5e82a 100644
--- a/test/socket_test.exs
+++ b/test/socket_test.exs
@@ -50,7 +50,12 @@ defmodule KafkaEx.Socket.Test do
     defp listen(socket) do
       case :ssl.transport_accept(socket) do
         {:ok, conn} ->
-          {:ok, _socket} = :ssl.handshake(conn)
+          if opt_version_21_plus? do
+            {:ok, _socket} = :ssl.handshake(conn)
+          else
+            :ok = :ssl.ssl_accept(conn)
+          end
+
           pid = spawn_link(fn -> recv(conn) end)
           :ssl.controlling_process(socket, pid)
 
@@ -70,6 +75,11 @@ defmodule KafkaEx.Socket.Test do
           :ok
       end
     end
+
+    defp opt_version_21_plus? do
+      {version, _} = System.otp_release() |> Float.parse()
+      version >= 21
+    end
   end
 
   setup_all do