diff --git a/.circleci/config.yml b/.circleci/config.yml
index d5a8ee3c2..a501982b6 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -34,6 +34,14 @@ jobs:
             make install-deps && make fetch-wheels
             PKG_DIR=~/project make requirements
 
+      - run:
+          name: Ensure that build-requirements.txt and requirements.txt are in sync.
+          command: |
+            cd ~/project
+            # Return 1 if unstaged changes exist (after `make requirements` in the 
+            # previous run step), else return 0.
+            git diff --quiet
+
       - run:
           name: Tag and make source tarball
           command: |