diff --git a/lua/snacks/picker/config/sources.lua b/lua/snacks/picker/config/sources.lua
index 96718796..331b5704 100644
--- a/lua/snacks/picker/config/sources.lua
+++ b/lua/snacks/picker/config/sources.lua
@@ -333,7 +333,8 @@ M.git_status = {
   },
 }
 
----@type snacks.picker.git.Config
+---@class snacks.picker.git.diff.Config: snacks.picker.git.Config
+---@field base? string base commit/branch/tag to diff against (default: HEAD)
 M.git_diff = {
   finder = "git_diff",
   format = "file",
diff --git a/lua/snacks/picker/source/git.lua b/lua/snacks/picker/source/git.lua
index 587a5554..7ea763de 100644
--- a/lua/snacks/picker/source/git.lua
+++ b/lua/snacks/picker/source/git.lua
@@ -253,11 +253,14 @@ function M.status(opts, ctx)
   }, ctx)
 end
 
----@param opts snacks.picker.git.Config
+---@param opts snacks.picker.git.diff.Config
 ---@type snacks.picker.finder
 function M.diff(opts, ctx)
   local args =
     M.git("diff", "--no-color", "--no-ext-diff", { args = { "-c", "diff.noprefix=false", "--no-pager" } }, opts)
+  if opts.base then
+    vim.list_extend(args, { "--merge-base", opts.base })
+  end
   local file, line ---@type string?, number?
   local header, hunk = {}, {} ---@type string[], string[]
   local header_len = 4