diff --git a/.github/workflows/php.yml b/.github/workflows/php.yml
index 81a6aec..d1a4ece 100644
--- a/.github/workflows/php.yml
+++ b/.github/workflows/php.yml
@@ -9,7 +9,7 @@ on:
 jobs:
   build:
 
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-18.04
     
     strategy:
       matrix: