diff --git a/lib/nerdtree/flag_set.vim b/lib/nerdtree/flag_set.vim
index f9d36ad..9d8d335 100644
--- a/lib/nerdtree/flag_set.vim
+++ b/lib/nerdtree/flag_set.vim
@@ -12,7 +12,7 @@ function! s:FlagSet.addFlag(scope, flag)
 endfunction
 
 "FUNCTION: FlagSet.clearFlags(scope) {{{1
-function! s:FlagSet.clearFlags(scope, flag)
+function! s:FlagSet.clearFlags(scope)
     let self._flags[a:scope] = []
 endfunction