diff --git a/README.md b/README.md
index 53b404d..82c5609 100644
--- a/README.md
+++ b/README.md
@@ -158,21 +158,29 @@ onedark.vim exposes `onedark#extend_highlight` and `onedark#set_highlight` funct
 
 `onedark#extend_highlight` allows you to customize individual aspects of onedark.vim's existing highlight groups, overriding only the keys you provide. (To completely redefine/override an existing highlight group, see `onedark#set_highlight` below.)
 
-`onedark#extend_highlight`'s first argunment should be the name of a highlight group, and its second argument should be style data.
+`onedark#extend_highlight`'s first argunment should be the name of a highlight group, and its second argument should be **partial** style data.
 
-For example, if you want functions to be bold only in GUI mode, place the following lines **before** the `colorscheme onedark` line in your `~/.vimrc`:
+Place the following lines **before** the `colorscheme onedark` line in your `~/.vimrc`, then change the example overrides to suit your needs:
 
 ```vim
-if (has("autocmd") && has("gui_running"))
-  autocmd ColorScheme * call onedark#extend_highlight("Function", { "gui": "bold" })
-end
+if (has("autocmd"))
+  augroup colorextend
+    autocmd!
+    " Make `Function`s bold in GUI mode
+    autocmd ColorScheme * call onedark#extend_highlight("Function", { "gui": "bold" })
+    " Override the `Statement` foreground color in 256-color mode
+    autocmd ColorScheme * call onedark#extend_highlight("Statement", { "fg": { "cterm": 128 } })
+    " Override the `Identifier` background color in GUI mode
+    autocmd ColorScheme * call onedark#extend_highlight("Identifier", { "bg": { "gui": "#333333" } })
+  augroup END
+endif
 ```
 
 #### `onedark#set_highlight`
 
 `onedark#set_highlight` allows you to completely redefine/override highlight groups of your choosing.
 
-`onedark#set_highlight`'s first argument should be the name of a highlight group, and its second argument should be style data.
+`onedark#set_highlight`'s first argument should be the name of a highlight group, and its second argument should be **complete** style data.
 
 For example, to remove the background color only when running in terminals (outside GUI mode and for use in transparent terminals,) place the following lines **before** the `colorscheme onedark` line in your `~/.vimrc`:
 
@@ -183,12 +191,17 @@ For example, to remove the background color only when running in terminals (outs
 " `cterm` is the color code used in 256-color mode
 " `cterm16` is the color code used in 16-color mode
 if (has("autocmd") && !has("gui_running"))
-  let s:white = { "gui": "#ABB2BF", "cterm": "145", "cterm16" : "7" }
-  autocmd ColorScheme * call onedark#set_highlight("Normal", { "fg": s:white }) " No `bg` setting
-end
+  augroup colorset
+    autocmd!
+    let s:white = { "gui": "#ABB2BF", "cterm": "145", "cterm16" : "7" }
+    autocmd ColorScheme * call onedark#set_highlight("Normal", { "fg": s:white }) " `bg` will not be styled since there is no `bg` setting
+  augroup END
+endif
 ```
 
-Finally, you can also override a color across all highlights by adding color definitions to the `g:onedark_color_overrides` dictionary in your `~/.vimrc` like so:
+#### Global color overrides
+
+You can override colors across all highlights by adding color definitions to the `g:onedark_color_overrides` dictionary in your `~/.vimrc` like so:
 
 ```vim
 let g:onedark_color_overrides = {
diff --git a/colors/onedark.vim b/colors/onedark.vim
index be0faab..23f5a0e 100644
--- a/colors/onedark.vim
+++ b/colors/onedark.vim
@@ -71,7 +71,21 @@ endif
 " Which in turn was based on one found in hemisu: https://github.com/noahfrederick/vim-hemisu/
 let s:group_colors = {} " Cache of default highlight group settings, for later reference via `onedark#extend_highlight`
 function! s:h(group, style, ...)
-  let a:highlight = a:0 > 0 ? extend(s:group_colors[a:group], a:style) : a:style
+  if (a:0 > 0) " Will be true if we got here from onedark#extend_highlight
+    let a:highlight = s:group_colors[a:group]
+    for style_type in ["fg", "bg", "sp"]
+      if (has_key(a:style, style_type))
+        let l:default_style = (has_key(a:highlight, style_type) ? a:highlight[style_type] : { "cterm16": "NONE", "cterm": "NONE", "gui": "NONE" })
+        let a:highlight[style_type] = extend(l:default_style, a:style[style_type])
+      endif
+    endfor
+    if (has_key(a:style, "gui"))
+      let a:highlight.gui = a:style.gui
+    endif
+  else
+    let a:highlight = a:style
+    let s:group_colors[a:group] = a:highlight " Cache default highlight group settings
+  endif
 
   if g:onedark_terminal_italics == 0
     if has_key(a:highlight, "cterm") && a:highlight["cterm"] == "italic"
@@ -98,8 +112,6 @@ function! s:h(group, style, ...)
     \ "ctermfg=" . l:ctermfg
     \ "ctermbg=" . l:ctermbg
     \ "cterm="   (has_key(a:highlight, "cterm") ? a:highlight.cterm    : "NONE")
-
-  let s:group_colors[a:group] = a:highlight
 endfunction
 
 " public {{{