diff --git a/.github/workflows/check.yml b/.github/workflows/check.yml
index 93b630a..676a5b7 100644
--- a/.github/workflows/check.yml
+++ b/.github/workflows/check.yml
@@ -37,8 +37,8 @@ jobs:
         env:
           MSG: ${{needs.check-outdated.outputs.msg}}
         run: |
-          nix develop .#ci -c curl -XPOST https://slack.com/api/chat.postMessage \
+          nix develop .#ci -c 'curl -XPOST https://slack.com/api/chat.postMessage \
             -H "Authorization: Bearer ${{ env.SLACK_TOKEN }}" \
             # you can change 'libraries' to the channel dedicated to the library, if there is one
             -d "channel=libraries" \
-            -d "text=$MSG"
+            -d "text=$MSG"'