diff --git a/.circleci/config.yml b/.circleci/config.yml
index 3875d98c..a932ccb3 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -62,7 +62,7 @@ executors:
     working_directory: ~/repo
   mac:
     macos:
-      xcode: "11.4.0"
+      xcode: "10.1.0"
     environment:
       <<: *opam_env
       OPAM_VERSION: 2.0.5
@@ -73,12 +73,12 @@ commands:
     steps:
       - restore_cache:
           keys:
-          - v1-opam-cache-{{ arch }}-v0
+          - v2-opam-cache-{{ arch }}-v0
 
   save-opam-cache:
     steps:
       - save_cache:
-          key: v1-opam-cache-{{ arch }}-v0
+          key: v2-opam-cache-{{ arch }}-v0
           paths:
             - ~/.opam
             - _opam