diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index aab98918..2cf06f06 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -12,7 +12,7 @@ on:
 jobs:
   tests:
     name: Tests PHP ${{ matrix.php }}, Symfony ${{ matrix.symfony }}
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-18.04
 
     strategy:
       matrix: