diff --git a/README.md b/README.md
index 07de881d..dd311b55 100644
--- a/README.md
+++ b/README.md
@@ -126,7 +126,7 @@ formatting.
 | GLSL | [glslang](https://github.com/KhronosGroup/glslang), [glslls](https://github.com/svenstaro/glsl-language-server) |
 | Go | [gofmt](https://golang.org/cmd/gofmt/), [goimports](https://godoc.org/golang.org/x/tools/cmd/goimports), [go vet](https://golang.org/cmd/vet/) !!, [golint](https://godoc.org/github.com/golang/lint), [gotype](https://godoc.org/golang.org/x/tools/cmd/gotype) !!, [gometalinter](https://github.com/alecthomas/gometalinter) !!, [go build](https://golang.org/cmd/go/) !!, [gosimple](https://github.com/dominikh/go-tools/tree/master/cmd/gosimple) !!, [staticcheck](https://github.com/dominikh/go-tools/tree/master/cmd/staticcheck) !! |
 | GraphQL | [eslint](http://eslint.org/), [gqlint](https://github.com/happylinks/gqlint), [prettier](https://github.com/prettier/prettier) |
-| Hack | [hack](http://hacklang.org/), [hackfmt](https://github.com/facebook/hhvm/tree/master/hphp/hack/hackfmt), [hhast](https://github.com/hhvm/hhast) |
+| Hack | [hack](http://hacklang.org/), [hackfmt](https://github.com/facebook/hhvm/tree/master/hphp/hack/hackfmt), [hhast](https://github.com/hhvm/hhast) (disabled by default; see `:help ale-integration-hack`) |
 | Haml | [haml-lint](https://github.com/brigade/haml-lint) |
 | Handlebars | [ember-template-lint](https://github.com/rwjblue/ember-template-lint) |
 | Haskell | [brittany](https://github.com/lspitzner/brittany), [ghc](https://www.haskell.org/ghc/), [cabal-ghc](https://www.haskell.org/cabal/), [stack-ghc](https://haskellstack.org/), [stack-build](https://haskellstack.org/) !!, [ghc-mod](https://github.com/DanielG/ghc-mod), [stack-ghc-mod](https://github.com/DanielG/ghc-mod), [hlint](https://hackage.haskell.org/package/hlint), [hdevtools](https://hackage.haskell.org/package/hdevtools), [hfmt](https://github.com/danstiner/hfmt) |
diff --git a/autoload/ale/linter.vim b/autoload/ale/linter.vim
index 683d506a..ab86d77e 100644
--- a/autoload/ale/linter.vim
+++ b/autoload/ale/linter.vim
@@ -26,11 +26,13 @@ let s:default_ale_linter_aliases = {
 "
 " Only cargo is enabled for Rust by default.
 " rpmlint is disabled by default because it can result in code execution.
+" hhast is disabled by default because it executes code in the project root.
 "
 " NOTE: Update the g:ale_linters documentation when modifying this.
 let s:default_ale_linters = {
 \   'csh': ['shell'],
 \   'go': ['gofmt', 'golint', 'go vet'],
+\   'hack': ['hack'],
 \   'help': [],
 \   'perl': ['perlcritic'],
 \   'python': ['flake8', 'mypy', 'pylint'],
diff --git a/doc/ale-hack.txt b/doc/ale-hack.txt
index a8027424..4776b8cf 100644
--- a/doc/ale-hack.txt
+++ b/doc/ale-hack.txt
@@ -1,5 +1,14 @@
 ===============================================================================
 ALE Hack Integration                                         *ale-hack-options*
+                                                         *ale-integration-hack*
+
+  HHAST is disabled by default, as it executes code in the project root.
+
+  Currently linters must be enabled globally.  HHAST can be enabled with:
+
+>
+  let g:ale_linters = {'hack': ['hack', 'hhast']}
+<
 
 ===============================================================================
 hack                                                            *ale-hack-hack*
diff --git a/doc/ale.txt b/doc/ale.txt
index b60c3da0..c360d3bd 100644
--- a/doc/ale.txt
+++ b/doc/ale.txt
@@ -1214,6 +1214,7 @@ g:ale_linters                                                   *g:ale_linters*
   {
   \   'csh': ['shell'],
   \   'go': ['gofmt', 'golint', 'go vet'],
+  \   'hack': ['hack'],
   \   'help': [],
   \   'perl': ['perlcritic'],
   \   'python': ['flake8', 'mypy', 'pylint'],