diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index cd49f4cd..9f8d1044 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -45,6 +45,7 @@ jobs:
           - 1.18.2
           - 1.19.2
           - 1.20.3
+          - 1.21.0
         include:
           - crystal: nightly
             stable: false