diff --git a/contrib/lualibs/mympd/50-util.lua b/contrib/lualibs/mympd/50-util.lua
index d23785bec..2c595fe17 100644
--- a/contrib/lualibs/mympd/50-util.lua
+++ b/contrib/lualibs/mympd/50-util.lua
@@ -119,6 +119,7 @@ end
 
 --- Read an ascii file
 -- @param path Filename
+-- @return File content or nil on error
 function mympd.read_file(path)
   local file = io.open(path, "r")
   if not file then