diff --git a/autoload/airline/builder.vim b/autoload/airline/builder.vim
index 345297b1..c09df414 100644
--- a/autoload/airline/builder.vim
+++ b/autoload/airline/builder.vim
@@ -133,11 +133,8 @@ function! airline#builder#should_change_group(group1, group2)
   endif
   let color1 = airline#highlighter#get_highlight(a:group1)
   let color2 = airline#highlighter#get_highlight(a:group2)
-  if g:airline_gui_mode ==# 'gui'
-    return color1[1] != color2[1] || color1[0] != color2[0]
-  else
-    return color1[3] != color2[3] || color1[2] != color2[2]
-  endif
+  return color1[1] != color2[1] || color1[0] != color2[0]
+      \ ||  color1[2] != color2[2] || color1[3] != color2[3]
 endfunction
 
 function! s:get_transitioned_seperator(self, prev_group, group, side)
diff --git a/autoload/airline/highlighter.vim b/autoload/airline/highlighter.vim
index 4e121c2c..e0ace222 100644
--- a/autoload/airline/highlighter.vim
+++ b/autoload/airline/highlighter.vim
@@ -12,7 +12,7 @@ let s:separators = {}
 let s:accents = {}
 let s:hl_groups = {}
 
-function! s:gui2cui(rgb, fallback)
+function! s:gui2cui(rgb, fallback) abort
   if a:rgb == ''
     return a:fallback
   elseif match(a:rgb, '^\%(NONE\|[fb]g\)$') > -1
@@ -22,7 +22,7 @@ function! s:gui2cui(rgb, fallback)
   return airline#msdos#round_msdos_colors(rgb)
 endfunction
 
-function! s:group_not_done(list, name)
+function! s:group_not_done(list, name) abort
   if index(a:list, a:name) == -1
     call add(a:list, a:name)
     return 1
@@ -34,17 +34,14 @@ function! s:group_not_done(list, name)
   endif
 endfu
 
-function! s:get_syn(group, what)
-  if !exists("g:airline_gui_mode")
-    let g:airline_gui_mode = airline#init#gui_mode()
-  endif
+function! s:get_syn(group, what, mode) abort
   let color = ''
   if hlexists(a:group)
-    let color = synIDattr(synIDtrans(hlID(a:group)), a:what, g:airline_gui_mode)
+    let color = synIDattr(synIDtrans(hlID(a:group)), a:what, a:mode)
   endif
   if empty(color) || color == -1
-    " should always exists
-    let color = synIDattr(synIDtrans(hlID('Normal')), a:what, g:airline_gui_mode)
+    " should always exist
+    let color = synIDattr(synIDtrans(hlID('Normal')), a:what, a:mode)
     " however, just in case
     if empty(color) || color == -1
       let color = 'NONE'
@@ -53,46 +50,46 @@ function! s:get_syn(group, what)
   return color
 endfunction
 
-function! s:get_array(fg, bg, opts)
-  let opts=empty(a:opts) ? '' : join(a:opts, ',')
-  return g:airline_gui_mode ==# 'gui'
-        \ ? [ a:fg, a:bg, '', '', opts ]
-        \ : [ '', '', a:fg, a:bg, opts ]
+function! s:get_array(guifg, guibg, ctermfg, ctermbg, opts) abort
+  return [ a:guifg, a:guibg, a:ctermfg, a:ctermbg, empty(a:opts) ? '' : join(a:opts, ',') ]
 endfunction
 
-function! airline#highlighter#reset_hlcache()
+function! airline#highlighter#reset_hlcache() abort
   let s:hl_groups = {}
 endfunction
 
-function! airline#highlighter#get_highlight(group, ...)
-  let reverse = get(g:, 'airline_gui_mode', '') ==# 'gui'
-      \ ? synIDattr(synIDtrans(hlID(a:group)), 'reverse', 'gui')
-      \ : synIDattr(synIDtrans(hlID(a:group)), 'reverse', 'cterm')
-      \|| synIDattr(synIDtrans(hlID(a:group)), 'reverse', 'term')
+function! airline#highlighter#get_highlight(group, ...) abort
+  " only check for the cterm reverse attribute
+  " TODO: do we need to check all modes (gui, term, as well)?
+  let reverse = synIDattr(synIDtrans(hlID(a:group)), 'reverse', 'cterm')
   if get(g:, 'airline_highlighting_cache', 0) && has_key(s:hl_groups, a:group)
     let res = s:hl_groups[a:group]
     return reverse ? [ res[1], res[0], res[3], res[2], res[4] ] : res
   else
-    let fg = s:get_syn(a:group, 'fg')
-    let bg = s:get_syn(a:group, 'bg')
+    let ctermfg = s:get_syn(a:group, 'fg', 'cterm')
+    let ctermbg = s:get_syn(a:group, 'bg', 'cterm')
+    let guifg = s:get_syn(a:group, 'fg', 'gui')
+    let guibg = s:get_syn(a:group, 'bg', 'gui')
     let bold = synIDattr(synIDtrans(hlID(a:group)), 'bold')
     if reverse
-      let res = s:get_array(bg, fg, bold ? ['bold'] : a:000)
+      let res = s:get_array(guibg, guifg, ctermbg, ctermfg, bold ? ['bold'] : a:000)
     else
-      let res = s:get_array(fg, bg, bold ? ['bold'] : a:000)
+      let res = s:get_array(guifg, guibg, ctermfg, ctermbg, bold ? ['bold'] : a:000)
     endif
   endif
   let s:hl_groups[a:group] = res
   return res
 endfunction
 
-function! airline#highlighter#get_highlight2(fg, bg, ...)
-  let fg = s:get_syn(a:fg[0], a:fg[1])
-  let bg = s:get_syn(a:bg[0], a:bg[1])
-  return s:get_array(fg, bg, a:000)
+function! airline#highlighter#get_highlight2(fg, bg, ...) abort
+  let guifg = s:get_syn(a:fg[0], a:fg[1], 'gui')
+  let guibg = s:get_syn(a:bg[0], a:bg[1], 'gui')
+  let ctermfg = s:get_syn(a:fg[0], a:fg[1], 'cterm')
+  let ctermbg = s:get_syn(a:bg[0], a:bg[1], 'cterm')
+  return s:get_array(guifg, guibg, ctermfg, ctermbg, a:000)
 endfunction
 
-function! s:hl_group_exists(group)
+function! s:hl_group_exists(group) abort
   if !hlexists(a:group)
     return 0
   elseif empty(synIDattr(hlID(a:group), 'fg'))
@@ -101,7 +98,7 @@ function! s:hl_group_exists(group)
   return 1
 endfunction
 
-function! airline#highlighter#exec(group, colors)
+function! airline#highlighter#exec(group, colors) abort
   if pumvisible()
     return
   endif
@@ -114,11 +111,7 @@ function! airline#highlighter#exec(group, colors)
   if len(colors) == 4
     call add(colors, '')
   endif
-  if g:airline_gui_mode ==# 'gui'
-    let new_hi = [colors[0], colors[1], '', '', colors[4]]
-  else
-    let new_hi = ['', '', printf("%s", colors[2]), printf("%s", colors[3]), colors[4]]
-  endif
+  let new_hi = [colors[0], colors[1], printf('%s', colors[2]), printf('%s', colors[3]), colors[4]]
   let colors = s:CheckDefined(colors)
   if old_hi != new_hi || !s:hl_group_exists(a:group)
     let cmd = printf('hi %s%s', a:group, s:GetHiCmd(colors))
@@ -129,7 +122,7 @@ function! airline#highlighter#exec(group, colors)
   endif
 endfunction
 
-function! s:CheckDefined(colors)
+function! s:CheckDefined(colors) abort
   " Checks, whether the definition of the colors is valid and is not empty or NONE
   " e.g. if the colors would expand to this:
   " hi airline_c ctermfg=NONE ctermbg=NONE
@@ -161,7 +154,7 @@ function! s:CheckDefined(colors)
   return a:colors[0:1] + [fg, bg] + [a:colors[4]]
 endfunction
 
-function! s:GetHiCmd(list)
+function! s:GetHiCmd(list) abort
   " a:list needs to have 5 items!
   let res = ''
   let i = -1
@@ -186,7 +179,7 @@ function! s:GetHiCmd(list)
   return res
 endfunction
 
-function! s:exec_separator(dict, from, to, inverse, suffix)
+function! s:exec_separator(dict, from, to, inverse, suffix) abort
   if pumvisible()
     return
   endif
@@ -202,7 +195,7 @@ function! s:exec_separator(dict, from, to, inverse, suffix)
   call airline#highlighter#exec(group, colors)
 endfunction
 
-function! airline#highlighter#load_theme()
+function! airline#highlighter#load_theme() abort
   if pumvisible()
     return
   endif
@@ -217,16 +210,16 @@ function! airline#highlighter#load_theme()
   endif
 endfunction
 
-function! airline#highlighter#add_separator(from, to, inverse)
+function! airline#highlighter#add_separator(from, to, inverse) abort
   let s:separators[a:from.a:to] = [a:from, a:to, a:inverse]
   call <sid>exec_separator({}, a:from, a:to, a:inverse, '')
 endfunction
 
-function! airline#highlighter#add_accent(accent)
+function! airline#highlighter#add_accent(accent) abort
   let s:accents[a:accent] = 1
 endfunction
 
-function! airline#highlighter#highlight_modified_inactive(bufnr)
+function! airline#highlighter#highlight_modified_inactive(bufnr) abort
   if getbufvar(a:bufnr, '&modified')
     let colors = exists('g:airline#themes#{g:airline_theme}#palette.inactive_modified.airline_c')
           \ ? g:airline#themes#{g:airline_theme}#palette.inactive_modified.airline_c : []
@@ -240,7 +233,7 @@ function! airline#highlighter#highlight_modified_inactive(bufnr)
   endif
 endfunction
 
-function! airline#highlighter#highlight(modes, ...)
+function! airline#highlighter#highlight(modes, ...) abort
   let bufnr = a:0 ? a:1 : ''
   let p = g:airline#themes#{g:airline_theme}#palette
 
diff --git a/autoload/airline/init.vim b/autoload/airline/init.vim
index fc47e3e8..3e29da06 100644
--- a/autoload/airline/init.vim
+++ b/autoload/airline/init.vim
@@ -31,7 +31,6 @@ function! airline#init#bootstrap()
   call s:check_defined('g:airline_exclude_filenames', ['DebuggerWatch','DebuggerStack','DebuggerStatus'])
   call s:check_defined('g:airline_exclude_filetypes', [])
   call s:check_defined('g:airline_exclude_preview', 0)
-  call s:check_defined('g:airline_gui_mode', airline#init#gui_mode())
 
   call s:check_defined('g:airline_mode_map', {})
   call extend(g:airline_mode_map, {
@@ -185,10 +184,6 @@ function! airline#init#bootstrap()
   unlet g:airline#init#bootstrapping
 endfunction
 
-function! airline#init#gui_mode()
-  return has('gui_running') || (has("termguicolors") && &termguicolors == 1) ?  'gui' : 'cterm'
-endfunction
-
 function! airline#init#sections()
   let spc = g:airline_symbols.space
   if !exists('g:airline_section_a')
diff --git a/plugin/airline.vim b/plugin/airline.vim
index 5ffcfc89..c38dbcb3 100644
--- a/plugin/airline.vim
+++ b/plugin/airline.vim
@@ -99,7 +99,6 @@ function! s:on_colorscheme_changed()
   call s:init()
   unlet! g:airline#highlighter#normal_fg_hi
   call airline#highlighter#reset_hlcache()
-  let g:airline_gui_mode = airline#init#gui_mode()
   if !s:theme_in_vimrc
     call airline#switch_matching_theme()
   endif
@@ -139,11 +138,7 @@ function! s:airline_toggle()
             \ | call <sid>on_window_changed('CmdwinEnter')
       autocmd CmdwinLeave * call airline#remove_statusline_func('airline#cmdwinenter')
 
-      autocmd GUIEnter,ColorScheme * call <sid>on_colorscheme_changed()
-      if exists("##OptionSet")
-        " Make sure that g_airline_gui_mode is refreshed
-        autocmd OptionSet termguicolors call <sid>on_colorscheme_changed()
-      endif
+      autocmd ColorScheme * call <sid>on_colorscheme_changed()
       " Set all statuslines to inactive
       autocmd FocusLost * call airline#update_statusline_focuslost()
       " Refresh airline for :syntax off
diff --git a/t/highlighter.vim b/t/highlighter.vim
index a38a5c67..36356e8d 100644
--- a/t/highlighter.vim
+++ b/t/highlighter.vim
@@ -6,9 +6,20 @@ describe 'highlighter'
     hi Foo2 ctermfg=3 ctermbg=4
     call airline#highlighter#add_separator('Foo1', 'Foo2', 0)
     let hl = airline#highlighter#get_highlight('Foo1_to_Foo2')
-    Expect hl == [ '', '', '4', '2', '' ]
+    Expect hl == [ 'NONE', 'NONE', '4', '2', '' ]
   end
 
+  if exists("+termguicolors")
+    it 'should create separator highlight groups with termguicolors'
+      set termguicolors
+      hi Foo1 guifg=#cd0000 guibg=#00cd00 ctermfg=1 ctermbg=2
+      hi Foo2 guifg=#cdcd00 guibg=#0000ee ctermfg=3 ctermbg=4
+      call airline#highlighter#add_separator('Foo1', 'Foo2', 0)
+      let hl = airline#highlighter#get_highlight('Foo1_to_Foo2')
+      Expect hl == [ '#0000ee', '#00cd00', '4', '2', '' ]
+    end
+  endif
+
   it 'should populate accent colors'
     Expect exists('g:airline#themes#dark#palette.normal.airline_c_red') to_be_false
     Expect hlID('airline_c_red') == 0
diff --git a/t/themes.vim b/t/themes.vim
index bff302b8..6e50d08f 100644
--- a/t/themes.vim
+++ b/t/themes.vim
@@ -8,23 +8,42 @@ describe 'themes'
     call airline#highlighter#reset_hlcache()
     highlight Foo ctermfg=1 ctermbg=2
     let colors = airline#themes#get_highlight('Foo')
+    Expect colors[0] == 'NONE'
+    Expect colors[1] == 'NONE'
     Expect colors[2] == '1'
     Expect colors[3] == '2'
   end
 
+  if exists("+termguicolors")
+    it 'should extract correct colors with termguicolors'
+      call airline#highlighter#reset_hlcache()
+      set termguicolors
+      highlight Foo guifg=#cd0000 guibg=#00cd00 ctermfg=1 ctermbg=2
+      let colors = airline#themes#get_highlight('Foo')
+      Expect colors[0] == '#cd0000'
+      Expect colors[1] == '#00cd00'
+      Expect colors[2] == '1'
+      Expect colors[3] == '2'
+    end
+  endif
+
   it 'should extract from normal if colors unavailable'
     call airline#highlighter#reset_hlcache()
     highlight Normal ctermfg=100 ctermbg=200
     highlight Foo ctermbg=2
     let colors = airline#themes#get_highlight('Foo')
+    Expect colors[0] == 'NONE'
+    Expect colors[1] == 'NONE'
     Expect colors[2] == '100'
     Expect colors[3] == '2'
   end
 
   it 'should flip target group if it is reversed'
     call airline#highlighter#reset_hlcache()
-    highlight Foo ctermbg=222 ctermfg=103 term=reverse
+    highlight Foo ctermbg=222 ctermfg=103 cterm=reverse
     let colors = airline#themes#get_highlight('Foo')
+    Expect colors[0] == 'NONE'
+    Expect colors[1] == 'NONE'
     Expect colors[2] == '222'
     Expect colors[3] == '103'
   end
@@ -33,10 +52,10 @@ describe 'themes'
     call airline#highlighter#reset_hlcache()
     hi clear Normal
     let hl = airline#themes#get_highlight('Foo', 'bold', 'italic')
-    Expect hl == ['', '', 'NONE', 'NONE', 'bold,italic']
+    Expect hl == ['NONE', 'NONE', 'NONE', 'NONE', 'bold,italic']
 
     let hl = airline#themes#get_highlight2(['Foo','bg'], ['Foo','fg'], 'italic', 'bold')
-    Expect hl == ['', '', 'NONE', 'NONE', 'italic,bold']
+    Expect hl == ['NONE', 'NONE', 'NONE', 'NONE', 'italic,bold']
   end
 
   it 'should generate color map with mirroring'