diff --git a/.github/workflows/tests.yaml b/.github/workflows/tests.yaml
index 00a823a..6c29e34 100644
--- a/.github/workflows/tests.yaml
+++ b/.github/workflows/tests.yaml
@@ -4,7 +4,7 @@ on: [push, pull_request]
 
 jobs:
   test:
-    name: PHP ${{ matrix.php-version }}
+    name: PHP ${{ matrix.php-version }} test
 
     runs-on: ubuntu-18.04
 
@@ -22,6 +22,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
 
       - name: Install PHP with extensions
         uses: shivammathur/setup-php@v2
@@ -34,9 +36,46 @@ jobs:
         uses: ramsey/composer-install@v1
         with:
           composer-options: --prefer-dist
+        if: matrix.php-version > 7.1
 
       - name: Run Tests
         run: composer tests
+        if: matrix.php-version > 7.1
 
       - name: Check coding style
         run: composer coding-style
+        if: matrix.php-version > 7.1
+
+  bc-checker:
+    name: PHP ${{ matrix.php-version }} bc-checker
+
+    runs-on: ubuntu-18.04
+
+    strategy:
+      fail-fast: false
+      matrix:
+        php-version:
+          - 7.4
+          - 8.0
+          - 8.1
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+
+      - name: Install PHP with extensions
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-version }}
+          coverage: pcov
+          tools: composer:v2
+
+      - name: Install Composer dependencies
+        uses: ramsey/composer-install@v1
+        with:
+          composer-options: --prefer-dist
+
+      - name: Check backward compatibility
+        run: composer backward-compatibility-check
diff --git a/.gitignore b/.gitignore
index 3d2e854..061d072 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,3 +4,4 @@ composer.lock
 example.php
 atlassian-ide-plugin.xml
 build/*
+.phpunit.result.cache
diff --git a/composer.json b/composer.json
index 303c363..49c84c5 100644
--- a/composer.json
+++ b/composer.json
@@ -36,7 +36,8 @@
     },
     "require-dev": {
         "internations/kodierungsregelwerksammlung": "~0.35",
-        "phpunit/phpunit": "~7 || ~8 || ~9"
+        "phpunit/phpunit": "~7 || ~8 || ~9",
+        "roave/backward-compatibility-check": "^3 || ^4 || ^5 || ^6"
     },
     "autoload": {
         "psr-0": {
@@ -50,6 +51,7 @@
     },
     "scripts": {
         "tests": "phpunit",
-        "coding-style": "phpcs --standard=vendor/internations/kodierungsregelwerksammlung/ruleset.xml ./src/"
+        "coding-style": "phpcs --standard=vendor/internations/kodierungsregelwerksammlung/ruleset.xml ./src/",
+        "backward-compatibility-check": "roave-backward-compatibility-check"
     }
 }