diff --git a/plugin/fugitive.vim b/plugin/fugitive.vim
index 0c3affe..35dca8f 100644
--- a/plugin/fugitive.vim
+++ b/plugin/fugitive.vim
@@ -16,9 +16,15 @@ function! FugitiveGitDir(...) abort
     let dir = get(b:, 'git_dir', '')
     if empty(dir) && (empty(bufname('')) || &buftype =~# '^\%(nofile\|acwrite\|quickfix\|prompt\)$')
       return FugitiveExtractGitDir(getcwd())
+    elseif !exists('b:git_dir') && empty(&buftype)
+      let b:git_dir = FugitiveExtractGitDir(expand('%:p'))
+      return b:git_dir
     endif
     return dir
   elseif type(a:1) == type(0)
+    if a:1 == bufnr('') && !exists('b:git_dir') && empty(&buftype)
+      let b:git_dir = FugitiveExtractGitDir(expand('%:p'))
+    endif
     return getbufvar(a:1, 'git_dir')
   elseif type(a:1) == type('')
     return substitute(s:Slash(a:1), '/$', '', '')