diff --git a/.github/workflows/integrate.yml b/.github/workflows/integrate.yml
index 96884d7..198528c 100644
--- a/.github/workflows/integrate.yml
+++ b/.github/workflows/integrate.yml
@@ -70,6 +70,10 @@ jobs:
         php-version:
           - "7.4"
 
+        phpunit-version:
+          - "6.0.0"
+          - "7.0.0"
+
         dependencies:
           - "lowest"
           - "locked"
@@ -97,6 +101,9 @@ jobs:
           key: "php-${{ matrix.php-version }}-composer-${{ matrix.dependencies }}-${{ hashFiles('**/composer.lock') }}"
           restore-keys: "php-${{ matrix.php-version }}-composer-${{ matrix.dependencies }}-"
 
+      - name: "Require phpunit/phpunit"
+        run: "composer require --dev phpunit/phpunit:^${{ matrix.phpunit-version }} --update-with-dependencies"
+
       - name: "Install lowest dependencies with composer"
         if: "matrix.dependencies == 'lowest'"
         run: "composer update --no-interaction --no-progress --no-suggest --prefer-lowest"
@@ -112,6 +119,9 @@ jobs:
       - name: "Show phpstan/phpstan version"
         run: "vendor/bin/phpstan --version"
 
+      - name: "Show phpunit/phpunit version"
+        run: "vendor/bin/phpunit --version"
+
       - name: "Create cache directory for phpstan/phpstan"
         run: "mkdir -p .build/phpstan"