diff --git a/.github/workflows/ct.yml b/.github/workflows/ct.yml
index c5220d2..d923a86 100644
--- a/.github/workflows/ct.yml
+++ b/.github/workflows/ct.yml
@@ -14,7 +14,7 @@ permissions:
 
 jobs:
   ct:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - name: Install dependencies (Ubuntu)
         run: |-