diff --git a/README.mkd b/README.mkd
index 5e92f23..68e0a85 100644
--- a/README.mkd
+++ b/README.mkd
@@ -5,7 +5,7 @@ A Vim plugin which shows a git diff in the 'gutter' (sign column).  It shows whe
 Features:
 
 * Shows signs for added, modified, and removed lines.
-* Runs the diffs asynchronously in terminal Vim (7.4.1826+) and NeoVim.
+* Runs the diffs asynchronously in terminal Vim (7.4.1826+), NeoVim and MacVim GUI (7.4.1832+).
 * Ensures signs are always as up to date as possible (but without running more than necessary).
 * Quick jumping between blocks of changed lines ("hunks").
 * Stage/undo/preview individual hunks.
diff --git a/autoload/gitgutter/async.vim b/autoload/gitgutter/async.vim
index 443039c..bef80ec 100644
--- a/autoload/gitgutter/async.vim
+++ b/autoload/gitgutter/async.vim
@@ -1,5 +1,13 @@
 let s:jobs = {}
-let s:available = has('nvim') || (has('patch-7-4-1826') && !has('gui_running'))
+
+" MacVim requires 88f4fe0 but that commit doesn't have a specific patch
+" number. So look for the first subsequent Vim patch.
+"
+" gVim doesn't work properly with channels yet as far as I know.
+let s:available = has('nvim') || (
+      \ (has('gui_macvim') && has('patch-7-4-1832')) ||
+      \ (has('patch-7-4-1826') && !has('gui_running'))
+      \ )
 
 function! gitgutter#async#available()
   return s:available