diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 7fd9bde9..3360bab5 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -11,7 +11,7 @@ env:
 jobs:
   documents-build:
 
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-18.04
 
     steps:
     - uses: actions/checkout@v2