diff --git a/lua/gitsigns.lua b/lua/gitsigns.lua
index 58c9aaf..7987da4 100644
--- a/lua/gitsigns.lua
+++ b/lua/gitsigns.lua
@@ -128,14 +128,14 @@ local update = async(function(bufnr, bcache)
    local compare_object
    if bcache.commit then
 
-      compare_object = bcache.commit .. '^:' .. git_obj.relpath
+      compare_object = string.format('%s^:%s', bcache.commit, git_obj.relpath)
    else
       local stage = git_obj.has_conflicts and 1 or 0
-      compare_object = ':' .. tostring(stage) .. ':' .. git_obj.relpath
+      compare_object = string.format(':%d:%s', stage, git_obj.relpath)
    end
 
    if config.use_internal_diff then
-      if bcache.commit or not bcache.compare_text or config._refresh_staged_on_update then
+      if not bcache.compare_text or config._refresh_staged_on_update then
          bcache.compare_text = await(git_obj:get_show_text(compare_object))
       end
       bcache.hunks = diff.run_diff(bcache.compare_text, buftext, config.diff_algorithm)
@@ -160,11 +160,43 @@ end)
 
 local update_debounced
 
-local watch_index = function(bufnr, gitdir, on_change)
+local watch_index = function(bufnr, gitdir)
    dprint('Watching index', bufnr, 'watch_index')
    local index = gitdir .. util.path_sep .. 'index'
    local w = uv.new_fs_poll()
-   w:start(index, config.watch_index.interval, on_change)
+   w:start(index, config.watch_index.interval, void_async(function(err)
+      if err then
+         dprint('Index update error: ' .. err, bufnr, 'watcher_cb')
+         return
+      end
+      dprint('Index update', bufnr, 'watcher_cb')
+
+      local bcache = cache[bufnr]
+
+      if not bcache then
+
+
+
+         dprint(string.format('Buffer %s has detached, aborting', bufnr))
+         return
+      end
+
+      local git_obj = bcache.git_obj
+
+      await(git_obj:update_abbrev_head())
+
+      await(scheduler())
+      Status:update_head(bufnr, git_obj.abbrev_head)
+
+      if not await(git_obj:update_file_info()) then
+         dprint('File not changed', bufnr, 'watcher_cb')
+         return
+      end
+
+      bcache.compare_text = nil
+
+      await(update(bufnr, bcache))
+   end))
    return w
 end
 
@@ -432,32 +464,6 @@ local function get_buf_path(bufnr)
    return file
 end
 
-local function index_handler(cbuf)
-   return void_async(function(err)
-      if err then
-         dprint('Index update error: ' .. err, cbuf, 'watcher_cb')
-         return
-      end
-      dprint('Index update', cbuf, 'watcher_cb')
-      local bcache = cache[cbuf]
-      local git_obj = bcache.git_obj
-
-      await(git_obj:update_abbrev_head())
-
-      await(scheduler())
-      Status:update_head(cbuf, git_obj.abbrev_head)
-
-      if not await(git_obj:update_file_info()) then
-         dprint('File not changed', cbuf, 'watcher_cb')
-         return
-      end
-
-      bcache.compare_text = nil
-
-      await(update(cbuf, bcache))
-   end)
-end
-
 local function in_git_dir(file)
    for _, p in ipairs(vim.split(file, util.path_sep)) do
       if p == '.git' then
@@ -592,7 +598,7 @@ local attach = async(function(cbuf)
       compare_text = nil,
       hunks = {},
       staged_diffs = {},
-      index_watcher = watch_index(cbuf, git_obj.gitdir, index_handler(cbuf)),
+      index_watcher = watch_index(cbuf, git_obj.gitdir),
       git_obj = git_obj,
    }
 
diff --git a/teal/gitsigns.tl b/teal/gitsigns.tl
index c97e649..f6ca0a9 100644
--- a/teal/gitsigns.tl
+++ b/teal/gitsigns.tl
@@ -55,7 +55,7 @@ local record CacheEntry
   hunks         : {Hunk}
   staged_diffs  : {Hunk}
   pending_signs : {integer:Sign}
-  index_watcher : vim.loop.FSPollObj -- Timer object watching the files index
+  index_watcher : uv.FSPollObj -- Timer object watching the files index
   git_obj       : git.Obj
   commit        : string
 end
@@ -128,14 +128,14 @@ local update = async(function(bufnr: integer, bcache: CacheEntry)
   local compare_object: string
   if bcache.commit then
     -- Buffer is a fugutive commit so compare against the parent of the commit
-    compare_object = bcache.commit..'^:'..git_obj.relpath
+    compare_object = string.format('%s^:%s', bcache.commit, git_obj.relpath)
   else
     local stage = git_obj.has_conflicts and 1 or 0
-    compare_object = ':'..tostring(stage)..':'..git_obj.relpath
+    compare_object = string.format(':%d:%s', stage, git_obj.relpath)
   end
 
   if config.use_internal_diff then
-    if bcache.commit or not bcache.compare_text or config._refresh_staged_on_update then
+    if not bcache.compare_text or config._refresh_staged_on_update then
       bcache.compare_text = await(git_obj:get_show_text(compare_object))
     end
     bcache.hunks = diff.run_diff(bcache.compare_text, buftext, config.diff_algorithm)
@@ -160,11 +160,43 @@ end)
 -- Define in setup so it can be debounced on updatetime
 local update_debounced: function(integer)
 
-local watch_index = function(bufnr: integer, gitdir: string, on_change: function): uv.FSPollObj
+local watch_index = function(bufnr: integer, gitdir: string): uv.FSPollObj
   dprint('Watching index', bufnr, 'watch_index')
   local index = gitdir..util.path_sep..'index'
   local w = uv.new_fs_poll()
-  w:start(index, config.watch_index.interval, on_change)
+  w:start(index, config.watch_index.interval, void_async(function(err: string)
+    if err then
+      dprint('Index update error: '..err, bufnr, 'watcher_cb')
+      return
+    end
+    dprint('Index update', bufnr, 'watcher_cb')
+
+    local bcache = cache[bufnr]
+
+    if not bcache then
+      -- Very occasionally an external git operation may cause the buffer to
+      -- detach and update the index simultaneously. When this happens this
+      -- handler will trigger but there will be no cache.
+      dprint(string.format('Buffer %s has detached, aborting', bufnr))
+      return
+    end
+
+    local git_obj = bcache.git_obj
+
+    await(git_obj:update_abbrev_head())
+
+    await(scheduler())
+    Status:update_head(bufnr, git_obj.abbrev_head)
+
+    if not await(git_obj:update_file_info()) then
+      dprint('File not changed', bufnr, 'watcher_cb')
+      return
+    end
+
+    bcache.compare_text = nil -- Invalidate
+
+    await(update(bufnr, bcache))
+  end))
   return w
 end
 
@@ -432,32 +464,6 @@ local function get_buf_path(bufnr: integer): string, string
   return file
 end
 
-local function index_handler(cbuf: integer): function
-  return void_async(function(err: string)
-    if err then
-      dprint('Index update error: '..err, cbuf, 'watcher_cb')
-      return
-    end
-    dprint('Index update', cbuf, 'watcher_cb')
-    local bcache = cache[cbuf]
-    local git_obj = bcache.git_obj
-
-    await(git_obj:update_abbrev_head())
-
-    await(scheduler())
-    Status:update_head(cbuf, git_obj.abbrev_head)
-
-    if not await(git_obj:update_file_info()) then
-      dprint('File not changed', cbuf, 'watcher_cb')
-      return
-    end
-
-    bcache.compare_text = nil -- Invalidate
-
-    await(update(cbuf, bcache))
-  end)
-end
-
 local function in_git_dir(file: string): boolean
   for _, p in ipairs(vim.split(file, util.path_sep)) do
     if p == '.git' then
@@ -592,7 +598,7 @@ local attach = async(function(cbuf: integer)
     compare_text  = nil,
     hunks         = {},
     staged_diffs  = {},
-    index_watcher = watch_index(cbuf, git_obj.gitdir, index_handler(cbuf)),
+    index_watcher = watch_index(cbuf, git_obj.gitdir),
     git_obj       = git_obj
   }