diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index b6236ccc4..abeb68937 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -59,7 +59,7 @@ jobs:
           curl -sL https://deb.nodesource.com/setup_14.x | sudo bash -
           sudo apt install nodejs
           matrix_os=${{ matrix.os }}
-          case matrix_os in
+          case $matrix_os in
             ubuntu-18.04)
               os_name="ubuntu~bionic"
               ;;