diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ac34196cb..bac3256e7 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -7,7 +7,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        os: [ubuntu-latest]
+        os: [ubuntu-18.04]
         # TODO: python 2.6
         python-version: [2.7, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, pypy-2.7, pypy-3.6, pypy-3.7]
         python-impl: [cpython]
@@ -26,11 +26,11 @@ jobs:
           ytdl-test-set: download
           run-tests-ext: bat
         # jython
-        - os: ubuntu-latest
+        - os: ubuntu-18.04
           python-impl: jython
           ytdl-test-set: core
           run-tests-ext: sh
-        - os: ubuntu-latest
+        - os: ubuntu-18.04
           python-impl: jython
           ytdl-test-set: download
           run-tests-ext: sh