diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 1a235f763..ec601d57e 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -8,7 +8,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: ubuntu-20.04]
+        os: [ubuntu-20.04]
         python: # pyenv-action requires the exact version
           - 3.6.8
           - 3.7.9