diff --git a/.drone.yml b/.drone.yml
index 832867e..0a12b32 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -33,3 +33,6 @@ matrix:
   IMAGE_PHP:
     - fpfis/httpd-php-dev:5.6
     - fpfis/httpd-php-dev:7.1
+  COMPOSER_BOUNDARY:
+    - lowest
+    - highest
\ No newline at end of file