diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index b39dee6..3ccccbd 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -116,3 +116,16 @@ jobs:
           cd test-composer/vendor/roundcube/roundcubemail
           ls -lah plugins/acl/config.*
           if [ ! -f plugins/acl/config.inc.php ]; then echo 'Config file was not created' && exit 1; fi
+
+      - name: Test update - install plugin
+        run: |
+          cd test-composer
+          echo '// xxx no config update xxx' >> vendor/roundcube/roundcubemail/plugins/carddav/config.inc.php
+          composer update -v --prefer-dist --no-interaction --no-progress roundcube/carddav --prefer-lowest
+
+      - name: Test update - verify install
+        run: |
+          cd test-composer
+          ls -lah vendor/roundcube/roundcubemail/plugins/carddav/config.*
+          if [ ! -f vendor/roundcube/roundcubemail/plugins/carddav/config.inc.php ]; then echo 'Config file was deleted' && exit 1; fi
+          if ! grep -Fq 'xxx no config update xxx' vendor/roundcube/roundcubemail/plugins/carddav/config.inc.php; then echo 'Config file was replaced' && exit 1; fi
diff --git a/src/ExtensionInstaller.php b/src/ExtensionInstaller.php
index 8cfbd61..e24cd01 100644
--- a/src/ExtensionInstaller.php
+++ b/src/ExtensionInstaller.php
@@ -63,13 +63,19 @@ public function getInstallPath(PackageInterface $package)
 
     private function initializeRoundcubemailEnvironment(): void
     {
-        // initialize Roundcube environment
         if (!defined('INSTALL_PATH')) {
             define('INSTALL_PATH', $this->getRoundcubemailInstallPath() . '/');
         }
         require_once INSTALL_PATH . 'program/include/iniset.php';
     }
 
+    public function isInstalled(InstalledRepositoryInterface $repo, PackageInterface $package)
+    {
+        $this->setRoundcubemailInstallPath($repo);
+
+        return parent::isInstalled($repo, $package);
+    }
+
     public function install(InstalledRepositoryInterface $repo, PackageInterface $package)
     {
         $this->setRoundcubemailInstallPath($repo);