diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index b5bb0e9..86b9dc4 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -4,7 +4,7 @@ on: [push, pull_request]
 
 jobs:
   test:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-18.04
     strategy:
       matrix:
         python-version: