diff --git a/autoload/gitgutter/diff.vim b/autoload/gitgutter/diff.vim
index ff1df6c..5a8bc5a 100644
--- a/autoload/gitgutter/diff.vim
+++ b/autoload/gitgutter/diff.vim
@@ -140,7 +140,11 @@ function! gitgutter#diff#handler(bufnr, diff) abort
   endif
 
   call s:save_last_seen_change(a:bufnr)
-  execute "silent doautocmd" s:nomodeline "User GitGutter"
+  if exists('#User#GitGutter')
+    let g:gitgutter_hook_context = {'bufnr': a:bufnr}
+    execute 'doautocmd' s:nomodeline 'User GitGutter'
+    unlet g:gitgutter_hook_context
+  endif
 endfunction
 
 
diff --git a/doc/gitgutter.txt b/doc/gitgutter.txt
index 3e0df36..1e5e93e 100644
--- a/doc/gitgutter.txt
+++ b/doc/gitgutter.txt
@@ -159,6 +159,8 @@ event GitGutter.  You can listen for this event, for example:
 >
   autocmd User GitGutter call updateMyStatusLine()
 <
+A dictionary `g:gitgutter_hook_context` is made available during its execution,
+which contains an entry `bufnr` that contains the buffer number being updated.
 
 
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