diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 458114e6..985c5c79 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -5,7 +5,7 @@ on:
       - main
 jobs:
   build:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-18.04
     steps:
       - name: Checkout source code.
         uses: actions/checkout@v3