diff --git a/colors/onedark.vim b/colors/onedark.vim
index f5804c2..36aa700 100644
--- a/colors/onedark.vim
+++ b/colors/onedark.vim
@@ -72,46 +72,46 @@ endif
 let s:group_colors = {} " Cache of default highlight group settings, for later reference via `onedark#extend_highlight`
 function! s:h(group, style, ...)
   if (a:0 > 0) " Will be true if we got here from onedark#extend_highlight
-    let a:highlight = s:group_colors[a:group]
+    let s: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])
+        let l:default_style = (has_key(s:highlight, style_type) ? s:highlight[style_type] : { "cterm16": "NONE", "cterm": "NONE", "gui": "NONE" })
+        let s: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
+      let s: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
+    let s:highlight = a:style
+    let s:group_colors[a:group] = s:highlight " Cache default highlight group settings
   endif
 
   if g:onedark_terminal_italics == 0
-    if has_key(a:highlight, "cterm") && a:highlight["cterm"] == "italic"
-      unlet a:highlight.cterm
+    if has_key(s:highlight, "cterm") && s:highlight["cterm"] == "italic"
+      unlet s:highlight.cterm
     endif
-    if has_key(a:highlight, "gui") && a:highlight["gui"] == "italic"
-      unlet a:highlight.gui
+    if has_key(s:highlight, "gui") && s:highlight["gui"] == "italic"
+      unlet s:highlight.gui
     endif
   endif
 
   if g:onedark_termcolors == 16
-    let l:ctermfg = (has_key(a:highlight, "fg") ? a:highlight.fg.cterm16 : "NONE")
-    let l:ctermbg = (has_key(a:highlight, "bg") ? a:highlight.bg.cterm16 : "NONE")
+    let l:ctermfg = (has_key(s:highlight, "fg") ? s:highlight.fg.cterm16 : "NONE")
+    let l:ctermbg = (has_key(s:highlight, "bg") ? s:highlight.bg.cterm16 : "NONE")
   else
-    let l:ctermfg = (has_key(a:highlight, "fg") ? a:highlight.fg.cterm : "NONE")
-    let l:ctermbg = (has_key(a:highlight, "bg") ? a:highlight.bg.cterm : "NONE")
+    let l:ctermfg = (has_key(s:highlight, "fg") ? s:highlight.fg.cterm : "NONE")
+    let l:ctermbg = (has_key(s:highlight, "bg") ? s:highlight.bg.cterm : "NONE")
   endif
 
   execute "highlight" a:group
-    \ "guifg="   (has_key(a:highlight, "fg")    ? a:highlight.fg.gui   : "NONE")
-    \ "guibg="   (has_key(a:highlight, "bg")    ? a:highlight.bg.gui   : "NONE")
-    \ "guisp="   (has_key(a:highlight, "sp")    ? a:highlight.sp.gui   : "NONE")
-    \ "gui="     (has_key(a:highlight, "gui")   ? a:highlight.gui      : "NONE")
+    \ "guifg="   (has_key(s:highlight, "fg")    ? s:highlight.fg.gui   : "NONE")
+    \ "guibg="   (has_key(s:highlight, "bg")    ? s:highlight.bg.gui   : "NONE")
+    \ "guisp="   (has_key(s:highlight, "sp")    ? s:highlight.sp.gui   : "NONE")
+    \ "gui="     (has_key(s:highlight, "gui")   ? s:highlight.gui      : "NONE")
     \ "ctermfg=" . l:ctermfg
     \ "ctermbg=" . l:ctermbg
-    \ "cterm="   (has_key(a:highlight, "cterm") ? a:highlight.cterm    : "NONE")
+    \ "cterm="   (has_key(s:highlight, "cterm") ? s:highlight.cterm    : "NONE")
 endfunction
 
 " public {{{