diff --git a/lib/resolv.rb b/lib/resolv.rb
index 1044b95e68..56183b837d 100644
--- a/lib/resolv.rb
+++ b/lib/resolv.rb
@@ -188,7 +188,7 @@ class Resolv
         unless @initialized
           @name2addr = {}
           @addr2name = {}
-          open(@filename, 'rb') {|f|
+          File.open(@filename, 'rb') {|f|
             f.each {|line|
               line.sub!(/#.*/, '')
               addr, hostname, *aliases = line.split(/\s+/)