diff --git a/colors/iceberg.vim b/colors/iceberg.vim
index 3ef4e93..10e6394 100644
--- a/colors/iceberg.vim
+++ b/colors/iceberg.vim
@@ -5,7 +5,7 @@
 "
 " File:       iceberg.vim
 " Maintainer: cocopon <cocopon@me.com>
-" Modified:   2021-12-25 14:23+0900
+" Modified:   2021-12-28 09:50+0900
 " License:    MIT
 
 
@@ -119,6 +119,19 @@ if &background == 'light'
   hi TSMethod ctermfg=237 guifg=#505695
   hi TSURI cterm=underline ctermfg=31 gui=underline guifg=#3f83a6 term=underline
   hi ZenSpace ctermbg=125 guibg=#cc517a
+  hi DiagnosticUnderlineInfo cterm=underline ctermfg=31 gui=underline guisp=#3f83a6 term=underline
+  hi DiagnosticInfo ctermfg=31 guifg=#3f83a6
+  hi DiagnosticSignInfo ctermbg=253 ctermfg=31 guibg=#dcdfe7 guifg=#3f83a6
+  hi DiagnosticUnderlineHint cterm=underline ctermfg=244 gui=underline guisp=#8389a3 term=underline
+  hi DiagnosticHint ctermfg=244 guifg=#8389a3
+  hi DiagnosticSignHint ctermbg=253 ctermfg=244 guibg=#dcdfe7 guifg=#8389a3
+  hi DiagnosticUnderlineWarn cterm=underline ctermfg=130 gui=underline guisp=#c57339 term=underline
+  hi DiagnosticWarn ctermfg=130 guifg=#c57339
+  hi DiagnosticSignWarn ctermbg=253 ctermfg=130 guibg=#dcdfe7 guifg=#c57339
+  hi DiagnosticUnderlineError cterm=underline ctermfg=125 gui=underline guisp=#cc517a term=underline
+  hi DiagnosticError ctermfg=125 guifg=#cc517a
+  hi DiagnosticSignError ctermbg=253 ctermfg=125 guibg=#dcdfe7 guifg=#cc517a
+  hi DiagnosticFloatingHint ctermbg=251 ctermfg=237 guibg=#cad0de guifg=#33374c
   hi icebergALAccentRed ctermfg=125 guifg=#cc517a
 
   if has('nvim')
@@ -240,6 +253,19 @@ else
   hi TSMethod ctermfg=252 guifg=#a3adcb
   hi TSURI cterm=underline ctermfg=109 gui=underline guifg=#89b8c2 term=underline
   hi ZenSpace ctermbg=203 guibg=#e27878
+  hi DiagnosticUnderlineInfo cterm=underline ctermfg=109 gui=underline guisp=#89b8c2 term=underline
+  hi DiagnosticInfo ctermfg=109 guifg=#89b8c2
+  hi DiagnosticSignInfo ctermbg=235 ctermfg=109 guibg=#1e2132 guifg=#89b8c2
+  hi DiagnosticUnderlineHint cterm=underline ctermfg=242 gui=underline guisp=#6b7089 term=underline
+  hi DiagnosticHint ctermfg=242 guifg=#6b7089
+  hi DiagnosticSignHint ctermbg=235 ctermfg=242 guibg=#1e2132 guifg=#6b7089
+  hi DiagnosticUnderlineWarn cterm=underline ctermfg=216 gui=underline guisp=#e2a478 term=underline
+  hi DiagnosticWarn ctermfg=216 guifg=#e2a478
+  hi DiagnosticSignWarn ctermbg=235 ctermfg=216 guibg=#1e2132 guifg=#e2a478
+  hi DiagnosticUnderlineError cterm=underline ctermfg=203 gui=underline guisp=#e27878 term=underline
+  hi DiagnosticError ctermfg=203 guifg=#e27878
+  hi DiagnosticSignError ctermbg=235 ctermfg=203 guibg=#1e2132 guifg=#e27878
+  hi DiagnosticFloatingHint ctermbg=236 ctermfg=251 guibg=#3d425b guifg=#c6c8d1
   hi icebergALAccentRed ctermfg=203 guifg=#e27878
 
   if has('nvim')
diff --git a/src/iceberg.vim b/src/iceberg.vim
index ff9ef47..21382ef 100644
--- a/src/iceberg.vim
+++ b/src/iceberg.vim
@@ -594,6 +594,45 @@ function! s:create_colors(palette) abort
         \ }))
   " }}}
 
+  " [Neovim built-in diagnostics](https://neovim.io/doc/user/diagnostic.html) {{{
+  for [group, color] in items({
+        \   'Error': 'red',
+        \   'Hint': 'comment_fg',
+        \   'Info': 'lblue',
+        \   'Warn': 'orange',
+        \ })
+    call extend(rules, pgmnt#hi#group(
+          \ 'DiagnosticUnderline' . group, {
+          \   'cterm': 'underline',
+          \   'ctermfg': c[color],
+          \   'gui': 'underline',
+          \   'guisp': g[color],
+          \   'term': 'underline',
+          \ }))
+    call extend(rules, pgmnt#hi#group(
+          \ 'Diagnostic' . group, {
+          \   'ctermfg': c[color],
+          \   'guifg': g[color],
+          \ }))
+    call extend(rules, pgmnt#hi#group(
+          \ 'DiagnosticSign' . group, {
+          \   'ctermbg': c.linenr_bg,
+          \   'ctermfg': c[color],
+          \   'guibg': g.linenr_bg,
+          \   'guifg': g[color],
+          \ }))
+  endfor
+  " Info color is hard to read within floating window, so use normal text
+  " color instead.
+  call extend(rules, pgmnt#hi#group(
+        \ 'DiagnosticFloatingHint', {
+        \   'ctermbg': c.pmenu_bg,
+        \   'ctermfg': c.pmenu_fg,
+        \   'guibg': g.pmenu_bg,
+        \   'guifg': g.pmenu_fg,
+        \ }))
+  " }}}
+
   " Palettes for statusline plugins {{{
   call extend(rules, pgmnt#hi#group(
         \ 'icebergALAccentRed', {