diff --git a/.circleci/config.yml b/.circleci/config.yml
index 20a0bb53b0..d92d493c45 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -26,7 +26,20 @@ executors:
     working_directory: ~/repos/celo-monorepo/packages/celotool
     environment:
       GO_VERSION: "1.16.4"
-      CELO_MONOREPO_BRANCH_TO_TEST: master
+      # CELO_MONOREPO_COMMIT_OR_BRANCH should point to a monorepo commit which is known to work, so that
+      # our CI doesn't break due to another team making changes in monorepo.
+      # * It should be updated when:
+      #     (a) changes or additions are made to the blockchain e2e tests in celo-monorepo, or
+      #     (b) a new contracts release has been merged to monorepo's master
+      #    In the latter case, we need to check whether the new contract release breaks things and update the mycelo
+      #    contracts ABI and migrations accordingly if necessary.
+      # * When updating it, update the comment with (a) the branch or commit hash, (b) the date of the change, and
+      #   (c) the contracts release it includes (`RELEASE_TAG` in the monorepo)
+
+      # b16a2d472a7cf24858f9d8b33a7185c8b81a261a is the current commit on master as of August 25, 2021, and
+      # includes contracts release 5 (core-contracts.v5)
+      CELO_MONOREPO_COMMIT_OR_BRANCH: b16a2d472a7cf24858f9d8b33a7185c8b81a261a
+
       GITHUB_RSA_FINGERPRINT: SHA256:nThbg6kXUpJWGl7E1IGOCspRomTxdCARLviKw6E5SY8
 jobs:
   build-geth:
@@ -210,8 +223,10 @@ jobs:
             set -e
             mkdir ~/.ssh && ssh-keyscan github.com >> ~/.ssh/known_hosts
             ssh-keygen -F github.com -l -f ~/.ssh/known_hosts | grep "github.com RSA ${GITHUB_RSA_FINGERPRINT}"
-            git clone --depth 1 https://github.com/celo-org/celo-monorepo.git celo-monorepo -b ${CELO_MONOREPO_BRANCH_TO_TEST}
+            git clone --depth 1 https://github.com/celo-org/celo-monorepo.git celo-monorepo
             cd celo-monorepo
+            git fetch --depth 1 origin ${CELO_MONOREPO_COMMIT_OR_BRANCH}
+            git checkout ${CELO_MONOREPO_COMMIT_OR_BRANCH}
             yarn install || yarn install
             yarn build --scope @celo/celotool --include-filtered-dependencies
       - run: