diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index d8ea4dfe015940f2b159898850c926a0f870f7ec..ebc3d86258fb81d65aabe256e964ad80d4e4c577 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -58,7 +58,7 @@ jobs:
         runs-on: ubuntu-latest
         strategy:
             matrix:
-                python-version: [3.6, 3.7, 3.8, pypy3]
+                python-version: ["3.6", "3.7", "3.8", "3.9", pypy3]
         steps:
         -   uses: actions/checkout@v2
         -