diff --git a/autoload/airline/extensions/tabline/builder.vim b/autoload/airline/extensions/tabline/builder.vim
index 2ce97c7..d0a0a31 100644
--- a/autoload/airline/extensions/tabline/builder.vim
+++ b/autoload/airline/extensions/tabline/builder.vim
@@ -16,7 +16,7 @@ endfunction
 
 function! s:prototype.try_insert_title(index, group, pos, sep_size, force) dict
   let title = self.get_title(a:index)
-  let self._remaining_space -= s:strchars(s:evaluate_tabline(title)) + a:sep_size
+  let self._remaining_space -= airline#util#strchars(s:evaluate_tabline(title)) + a:sep_size
   if a:force || self._remaining_space >= 0
     let pos = a:pos
     if has_key(self, "get_pretitle")
@@ -37,7 +37,7 @@ function! s:prototype.try_insert_title(index, group, pos, sep_size, force) dict
 
     return 1
   else
-    let self._remaining_space += s:strchars(s:evaluate_tabline(title)) + a:sep_size
+    let self._remaining_space += airline#util#strchars(s:evaluate_tabline(title)) + a:sep_size
   endif
   return 0
 endfunction
@@ -58,15 +58,15 @@ endfunction
 
 function! s:prototype.build() dict
   if has_key(self, '_left_position')
-    let self._remaining_space = &columns - s:strchars(s:evaluate_tabline(self._build()))
+    let self._remaining_space = &columns - airline#util#strchars(s:evaluate_tabline(self._build()))
 
     let center_active = get(g:, 'airline#extensions#tabline#center_active', 0)
 
-    let sep_size = s:strchars(s:evaluate_tabline(self._context.left_sep))
-    let alt_sep_size = s:strchars(s:evaluate_tabline(self._context.left_alt_sep))
+    let sep_size = airline#util#strchars(s:evaluate_tabline(self._context.left_sep))
+    let alt_sep_size = airline#util#strchars(s:evaluate_tabline(self._context.left_alt_sep))
 
     let overflow_marker = get(g:, 'airline#extensions#tabline#overflow_marker', g:airline_symbols.ellipsis)
-    let overflow_marker_size = s:strchars(s:evaluate_tabline(overflow_marker))
+    let overflow_marker_size = airline#util#strchars(s:evaluate_tabline(overflow_marker))
     " Allow space for the markers before we begin filling in titles.
     let self._remaining_space -= 2 * overflow_marker_size
 
@@ -153,16 +153,6 @@ function! s:evaluate_tabline(tabline)
   return tabline
 endfunction
 
-" Compatibility wrapper for strchars, in case this vim version does not
-" have it natively
-function! s:strchars(str)
-  if exists('*strchars')
-    return strchars(a:str)
-  else
-    return strlen(substitute(a:str, '.', 'a', 'g'))
-  endif
-endfunction
-
 function! airline#extensions#tabline#builder#new(context)
   let builder = airline#builder#new(a:context)
   let builder._build = builder.build
diff --git a/autoload/airline/util.vim b/autoload/airline/util.vim
index e0bec92..23c44c4 100644
--- a/autoload/airline/util.vim
+++ b/autoload/airline/util.vim
@@ -86,3 +86,13 @@ else
     return 0
   endfunction
 endif
+
+" Compatibility wrapper for strchars, in case this vim version does not
+" have it natively
+function! airline#util#strchars(str)
+  if exists('*strchars')
+    return strchars(a:str)
+  else
+    return strlen(substitute(a:str, '.', 'a', 'g'))
+  endif
+endfunction