diff --git a/autoload/airline.vim b/autoload/airline.vim
index de66fbac..b4a88817 100644
--- a/autoload/airline.vim
+++ b/autoload/airline.vim
@@ -148,16 +148,18 @@ function! airline#check_mode(winnr)
     let w:airline_current_mode = get(g:airline_mode_map, '__')
   endif
 
-  if g:airline_detect_modified
-    if &modified
-      call add(l:mode, 'modified')
-    endif
+  if g:airline_detect_modified && &modified
+    call add(l:mode, 'modified')
   endif
 
   if g:airline_detect_paste && &paste
     call add(l:mode, 'paste')
   endif
 
+  if &readonly
+    call add(l:mode, 'readonly')
+  endif
+
   let mode_string = join(l:mode)
   if get(w:, 'airline_lastmode', '') != mode_string
     call airline#highlighter#highlight_modified_inactive(context.bufnr)