diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0d06d38..01ff143 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -61,6 +61,7 @@ jobs:
       run:
         if [[ -e build/envs.txt ]]; then touch build/envs.txt; fi;
         if [[ -e build/deps.txt ]]; then touch build/deps.txt; fi;
+        brew install mercurial
         make conda
 
     - name: make lint