diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 89732a9ccb..4ceb350762 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -7,7 +7,7 @@ lint:
       - schedules
       - pipelines
   before_script:
-    - printf "Package\x3a androguard fdroidserver python3-asn1crypto python3-ruamel.yaml\nPin\x3a release a=stretch-backports\nPin-Priority\x3a 500\n" > /etc/apt/preferences.d/debian-stretch-backports.pref
+    - printf "Package\x3a androguard fdroidserver python3-asn1crypto python3-ruamel.yaml yamllint\nPin\x3a release a=stretch-backports\nPin-Priority\x3a 500\n" > /etc/apt/preferences.d/debian-stretch-backports.pref
     - echo "deb http://deb.debian.org/debian/ stretch-backports main" > /etc/apt/sources.list.d/backports.list
     - apt-get update
     - apt-get -qy dist-upgrade
@@ -33,7 +33,8 @@ lint:
            fi;
         done;
         set -x;
-        apt-get install python3-colorama;
+        apt-get install python3-colorama yamllint;
+        for f in $files; do [[ $f == *'.yml' ]] && yamllint "$f"; done;
         ./tools/check-git-repo-availability.py $files;
         ./tools/audit-gradle.py $CHANGED;
         set +x;
diff --git a/.yamllint b/.yamllint
new file mode 100644
index 0000000000..a200904905
--- /dev/null
+++ b/.yamllint
@@ -0,0 +1,28 @@
+extends: default
+
+rules:
+  braces:
+    level: warning
+    max-spaces-inside: 1
+  brackets:
+    level: warning
+    max-spaces-inside: 1
+  colons:
+    level: warning
+  commas:
+    level: warning
+  comments: disable
+  comments-indentation: disable
+  document-start: disable
+  empty-lines: disable
+  hyphens:
+    level: warning
+  indentation:
+    level: warning
+    indent-sequences: consistent
+  line-length: disable
+  new-line-at-end-of-file:
+    level: warning
+  trailing-spaces:
+    level: warning
+  truthy: disable
diff --git a/srclibs/MinetestGame.yml b/srclibs/MinetestGame.yml
index b804fccdce..7e5a14fb29 100644
--- a/srclibs/MinetestGame.yml
+++ b/srclibs/MinetestGame.yml
@@ -1,2 +1,2 @@
 RepoType: git
-Repo: https://github.com/minetest/minetest_game.git
\ No newline at end of file
+Repo: https://github.com/minetest/minetest_game.git
diff --git a/srclibs/MozFennec.yml b/srclibs/MozFennec.yml
index 23ca06a538..d3c4e11377 100644
--- a/srclibs/MozFennec.yml
+++ b/srclibs/MozFennec.yml
@@ -1,2 +1,2 @@
 RepoType: hg
-Repo: https://hg.mozilla.org/releases/mozilla-release/
\ No newline at end of file
+Repo: https://hg.mozilla.org/releases/mozilla-release/
diff --git a/srclibs/MozFennecBeta.yml b/srclibs/MozFennecBeta.yml
index a1c2ba700e..e1e1c1c526 100644
--- a/srclibs/MozFennecBeta.yml
+++ b/srclibs/MozFennecBeta.yml
@@ -1,2 +1,2 @@
 RepoType: hg
-Repo: https://hg.mozilla.org/releases/mozilla-beta/
\ No newline at end of file
+Repo: https://hg.mozilla.org/releases/mozilla-beta/
diff --git a/srclibs/MozGlean.yml b/srclibs/MozGlean.yml
index 857e54280c..8352ee64fb 100644
--- a/srclibs/MozGlean.yml
+++ b/srclibs/MozGlean.yml
@@ -1,2 +1,3 @@
 RepoType: git
-Repo: https://github.com/mozilla/glean.git
\ No newline at end of file
+Repo: https://github.com/mozilla/glean.git
+
diff --git a/srclibs/StockFish.yml b/srclibs/StockFish.yml
index 6e86b31d9a..f31ab76278 100644
--- a/srclibs/StockFish.yml
+++ b/srclibs/StockFish.yml
@@ -1,5 +1,6 @@
-RepoType: git-svn
+#RepoType: git-svn
 #Repo:https://cuckoochess.googlecode.com/svn/trunk/
 #Subdir:DroidFish/jni/stockfish
 RepoType: git
 Repo: https://github.com/official-stockfish/Stockfish
+
diff --git a/srclibs/realm.yml b/srclibs/realm.yml
index bc0d80cd68..bb5c463105 100644
--- a/srclibs/realm.yml
+++ b/srclibs/realm.yml
@@ -3,4 +3,4 @@ Repo: https://github.com/realm/realm-js.git
 
 
 Prepare: |
-  git submodule update --init
\ No newline at end of file
+  git submodule update --init
diff --git a/tools/check-localized-metadata.py b/tools/check-localized-metadata.py
index e64d767cdf..6b8e0a6f78 100755
--- a/tools/check-localized-metadata.py
+++ b/tools/check-localized-metadata.py
@@ -5,7 +5,7 @@ import os
 import re
 import sys
 
-os.chdir(os.path.dirname(__file__) + '/../')
+os.chdir(os.path.join(os.path.dirname(__file__), '..'))
 
 count = 0
 
diff --git a/tools/check-metadata-summary-whitespace.py b/tools/check-metadata-summary-whitespace.py
index eff38a42eb..8bb9f23764 100755
--- a/tools/check-metadata-summary-whitespace.py
+++ b/tools/check-metadata-summary-whitespace.py
@@ -3,7 +3,7 @@
 import glob
 import os
 
-os.chdir(os.path.dirname(__file__) + '/../')
+os.chdir(os.path.join(os.path.dirname(__file__), '..'))
 
 for f in glob.glob('metadata/*/*/*.txt') +  glob.glob('metadata/*/*/*/*.txt'):
     if os.path.getsize(f) == 0: