diff --git a/autoload/airline.vim b/autoload/airline.vim
index b4a88817..81cf3b5f 100644
--- a/autoload/airline.vim
+++ b/autoload/airline.vim
@@ -156,7 +156,7 @@ function! airline#check_mode(winnr)
     call add(l:mode, 'paste')
   endif
 
-  if &readonly
+  if &readonly || ! &modifiable
     call add(l:mode, 'readonly')
   endif