diff --git a/.github/workflows/test-linux-extra.yml b/.github/workflows/test-linux-extra.yml
index f3ef0bbd6..9657f38d6 100644
--- a/.github/workflows/test-linux-extra.yml
+++ b/.github/workflows/test-linux-extra.yml
@@ -13,9 +13,8 @@ jobs:
   build:
     strategy:
       matrix:
-        image: [ubuntu:18.04, ubuntu:20.04]
-
-
+        image: ["ubuntu:18.04", "ubuntu:20.04"]
+        
     runs-on:  ubuntu-20.04
 
     steps: