diff --git a/.travis.yml b/.travis.yml
index 2354b969..e33e8efe 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -12,20 +12,24 @@ before_install:
 - mkdir -p ~/.local/bin
 - export PATH=$HOME/.local/bin:$PATH
 - travis_retry curl -L https://www.stackage.org/stack/linux-x86_64 | tar xz --wildcards --strip-components=1 -C ~/.local/bin '*/stack'
+- rvm use 2.1 --install --binary --fuzzy
 install:
-  - travis_wait 30 stack --no-terminal --install-ghc --copy-bins build
-  - stack --no-terminal install hlint
+- travis_wait 30 stack --no-terminal --install-ghc --copy-bins build
+- stack --no-terminal install hlint
+- cp hlint ~/.local/bin
+- gem install danger danger-hlint
 script:
 - stack --no-terminal test --only-dependencies
 - "./hlint '--ignore=Parse error' src"
 - "./hlint '--ignore=Parse error' app"
+- danger
 deploy:
   provider: releases
   api_key:
     secure: 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
   file:
-    - count
-    - plagiarism
+  - count
+  - plagiarism
   skip_cleanup: true
   on:
     tags: true
diff --git a/Dangerfile b/Dangerfile
new file mode 100644
index 00000000..1593c41e
--- /dev/null
+++ b/Dangerfile
@@ -0,0 +1,5 @@
+affected_files = git.added_files + git.modified_files
+
+haskell_files = affected_files.select { |file| file.end_with?('.hs') }
+
+hlint.lint(haskell_files, true)
diff --git a/lichen.cabal b/lichen.cabal
index 1931a6cc..6d060bd0 100644
--- a/lichen.cabal
+++ b/lichen.cabal
@@ -54,13 +54,13 @@ library
                      , blaze-markup
                      , clay
                      , jmacro
-  ghc-options:         -Wall -Werror -fwarn-incomplete-patterns
+  ghc-options:         -Wall -fwarn-incomplete-patterns
   default-language:    Haskell2010
 
 executable plagiarism
   hs-source-dirs:      app/plagiarism
   main-is:             Main.hs
-  ghc-options:         -threaded -rtsopts -with-rtsopts=-N -O2 -Wall -Werror
+  ghc-options:         -threaded -rtsopts -with-rtsopts=-N -O2 -Wall
   build-depends:       base
                      , lichen
   default-language:    Haskell2010
@@ -68,7 +68,7 @@ executable plagiarism
 executable count
   hs-source-dirs:      app/count
   main-is:             Main.hs
-  ghc-options:         -threaded -rtsopts -with-rtsopts=-N -O2 -Wall -Werror
+  ghc-options:         -threaded -rtsopts -with-rtsopts=-N -O2 -Wall
   build-depends:       base
                      , lichen
   default-language:    Haskell2010