diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0fa7c56..3df5e85 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -33,6 +33,11 @@ jobs:
         php-version:
           - "7.4"
           - "8.0"
+        deps:
+          - "highest"
+        include:
+          - php-version: "7.4"
+            deps: "lowest"
 
     services:
       mysql:
@@ -57,6 +62,8 @@ jobs:
 
       - name: Install composer dependencies
         uses: "ramsey/composer-install@v1"
+        with:
+          dependency-versions: ${{ matrix.deps }}
 
       - name: Run PHPUnit
         run: vendor/bin/phpunit
diff --git a/composer.json b/composer.json
index d828f61..3c50619 100644
--- a/composer.json
+++ b/composer.json
@@ -10,12 +10,12 @@
     "license": "MIT",
     "require": {
         "brick/geo": "dev-master",
-        "doctrine/orm": "^2.0"
+        "doctrine/orm": "^2.8"
     },
     "require-dev": {
         "doctrine/cache": "^1.11",
         "doctrine/data-fixtures": "^1.0",
-        "phpunit/phpunit": "^8.0 || ^9.0",
+        "phpunit/phpunit": "^9.0",
         "php-coveralls/php-coveralls": "^2.0",
         "vimeo/psalm": "4.3.1"
     },