diff --git a/.travis.yml b/.travis.yml
index 118b76630..8b2f38b90 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,41 +4,42 @@ language: python
 dist: xenial
 sudo: false
 python:
-    - "3.7"
+  - "3.7"
 
 cache:
-    directories:
-        - $HOME/.cache/pip
-        - $HOME/.virtualenvs
+  directories:
+    - $HOME/.cache/pip
+    - $HOME/.virtualenvs
 
 addons:
-    apt:
-        packages:
-            - graphviz
+  apt:
+    packages:
+      - graphviz
 
 env:
-    global:
-        PROTOBUF_VERSION=3.6.1
+  global:
+    PROTOBUF_VERSION=3.6.1
 
 install:
-    - pip install --upgrade pip wheel setuptools
-    - pip install poetry
-    - poetry install
-    # make sure poetry is installable without protobuf - install protoc later
-    - curl -LO "https://github.com/google/protobuf/releases/download/v${PROTOBUF_VERSION}/protoc-${PROTOBUF_VERSION}-linux-x86_64.zip"
-    - unzip "protoc-${PROTOBUF_VERSION}-linux-x86_64.zip" -d protoc
-    - export PATH="$(pwd)/protoc/bin:$PATH"
+  - pip install --upgrade pip wheel setuptools
+  - pip install poetry
+  - poetry install
+  # make sure poetry is installable without protobuf - install protoc later
+  - curl -LO "https://github.com/google/protobuf/releases/download/v${PROTOBUF_VERSION}/protoc-${PROTOBUF_VERSION}-linux-x86_64.zip"
+  - unzip "protoc-${PROTOBUF_VERSION}-linux-x86_64.zip" -d protoc
+  - export PATH="$(pwd)/protoc/bin:$PATH"
 
 script:
-    - poetry run make style_check
-    - poetry run make defs_check
-    - poetry run make gen_check
-    - ci/check_fixup.sh
+  - poetry run make style_check
+  - poetry run make defs_check
+  - poetry run make gen_check
+  - poetry run make yaml_check
+  - ci/check_fixup.sh
 
 notifications:
-    webhooks:
-        urls:
-            - http://ci-bot.satoshilabs.com:5000/travis
-    on_success: always
-    on_failure: always
-    on_start: always
+  webhooks:
+    urls:
+      - http://ci-bot.satoshilabs.com:5000/travis
+  on_success: always
+  on_failure: always
+  on_start: always
diff --git a/.yamllint.yml b/.yamllint.yml
index f2e2618cc..8406a326d 100644
--- a/.yamllint.yml
+++ b/.yamllint.yml
@@ -8,3 +8,6 @@ rules:
   line-length: disable
   # skip "---" at the beginning
   document-start: disable
+  comments-indentation: disable
+  indentation:
+    spaces: 2
diff --git a/Makefile b/Makefile
index 69c87606a..01a55dc3a 100644
--- a/Makefile
+++ b/Makefile
@@ -39,13 +39,13 @@ pystyle: ## apply code style on application sources and tests
 	@flake8 $(PY_FILES)
 	make -C python style
 
-changelog_check:  # check changelog format
+changelog_check: ## check changelog format
 	./tools/linkify-changelogs.py --check
 
-yaml_check:
+yaml_check: ## check yaml formatting
 	yamllint .
 
-changelog:  # fill out issue links in changelog
+changelog: ## fill out issue links in changelog
 	./tools/linkify-changelogs.py
 
 cstyle_check: ## run code style check on low-level C code
diff --git a/ci/prebuild.yml b/ci/prebuild.yml
index 33d53822a..2751e17ea 100644
--- a/ci/prebuild.yml
+++ b/ci/prebuild.yml
@@ -17,6 +17,11 @@ gen prebuild:
   script:
     - nix-shell --run "poetry run make gen_check"
 
+yaml prebuild:
+  stage: prebuild
+  script:
+    - nix-shell --run "poetry run make yaml_check"
+
 release commit messages prebuild:
   stage: prebuild
   before_script: []  # nothing needed