diff --git a/bitbucket-pipelines.yml b/bitbucket-pipelines.yml
index 903b04be..b7f177c7 100644
--- a/bitbucket-pipelines.yml
+++ b/bitbucket-pipelines.yml
@@ -27,7 +27,7 @@ definitions:
       - clientmodules
     script:
       - npm install --prefix client
-      - npm run lint --prefix client
+      - yarn run lint --prefix client
   - &unittest-python
     name: run python unit tests
     caches:
@@ -53,14 +53,14 @@ definitions:
     script:
     - echo "This pipeline rules!"
     - *setup-tests
-    - npm ci --prefix client
-    - npm run "install:cypress" --prefix client
+    - yarn install --frozen-lockfile --prefix client
+    - yarn run "install:cypress" --prefix client
     - psql -U $DATABASE_USER -h $DATABASE_HOST -c "create database $DATABASE_NAME"
     - python server/manage.py dummy_data
     - python server/manage.py runserver 2>&1 > /dev/null &
-    - npm run build --prefix client
+    - yarn run build --prefix client
     - curl http://localhost:8000/beta-login
-    - npm run --prefix client test:cypress:e2e
+    - yarn run --prefix client test:cypress:e2e
   - &frontend-test
     name: run cypress frontend tests
     caches:
@@ -72,12 +72,12 @@ definitions:
     - client/cypress/**/*.png
     - client/cypress/**/*.mp4
     script:
-    - npm ci --prefix client
-    - npm run "install:cypress" --prefix client
-    - npm run dev --prefix client 2>&1 > /dev/null &
+    - yarn install --frozen-lockfile --prefix client
+    - yarn run "install:cypress" --prefix client
+    - yarn run dev --prefix client 2>&1 > /dev/null &
     - sleep 30
     - curl http://localhost:8080/beta-login
-    - npm run --prefix client test:cypress:frontend
+    - yarn run --prefix client test:cypress:frontend
   - &frontend-test-parallel
     name: run cypress frontend tests
     caches:
@@ -89,9 +89,9 @@ definitions:
     - client/cypress/**/*.png
     - client/cypress/**/*.mp4
     script:
-    - npm ci --prefix client
-    - npm run "install:cypress" --prefix client
-    - npm run dev --prefix client 2>&1 > /dev/null &
+    - yarn install --frozen-lockfile --prefix client
+    - yarn run "install:cypress" --prefix client
+    - yarn run dev --prefix client 2>&1 > /dev/null &
     - sleep 30
     - curl http://localhost:8080/beta-login
     - source bin/run-cypress-parallel.sh
@@ -105,7 +105,7 @@ definitions:
     - *setup-tests
     - npm install --prefix client
     - cd client
-    - npm run test:unit
+    - yarn run test:unit
   - &deploy-dev
     name: deploy to dev on Heroku
     deployment: dev