diff --git a/lua/config/statusline.lua b/lua/config/statusline.lua
index aad6564..9b4c6fa 100644
--- a/lua/config/statusline.lua
+++ b/lua/config/statusline.lua
@@ -7,6 +7,7 @@ local function spell()
 end
 
 local function trailing_space()
+  -- Get the positions of trailing whitespaces from plugin 'jdhao/whitespace.nvim'.
   local trailing_space_pos = vim.b.trailing_whitespace_pos
 
   local msg = ""
@@ -19,6 +20,30 @@ local function trailing_space()
   return msg
 end
 
+local function mixed_indent()
+  local space_pat = [[\v^ +]]
+  local tab_pat = [[\v^\t+]]
+  local space_indent = vim.fn.search(space_pat, 'nwc')
+  local tab_indent = vim.fn.search(tab_pat, 'nwc')
+  local mixed = (space_indent > 0 and tab_indent > 0)
+  local mixed_same_line
+  if not mixed then
+    mixed_same_line = vim.fn.search([[\v^(\t+ | +\t)]], 'nwc')
+    mixed = mixed_same_line > 0
+  end
+  if not mixed then return '' end
+  if mixed_same_line ~= nil and mixed_same_line > 0 then
+     return 'MI:'..mixed_same_line
+  end
+  local space_indent_cnt = vim.fn.searchcount({pattern=space_pat, max_count=1e3}).total
+  local tab_indent_cnt =  vim.fn.searchcount({pattern=tab_pat, max_count=1e3}).total
+  if space_indent_cnt > tab_indent_cnt then
+    return 'MI:'..tab_indent
+  else
+    return 'MI:'..space_indent
+  end
+end
+
 require("lualine").setup({
   options = {
     icons_enabled = true,
@@ -60,7 +85,11 @@ require("lualine").setup({
       {
         trailing_space,
         color = "WarningMsg"
-      }
+      },
+      {
+        mixed_indent,
+        color = "WarningMsg"
+      },
     },
   },
   inactive_sections = {