diff --git a/lib/resolv.rb b/lib/resolv.rb
index 3df88e4f9c..830ba160d2 100644
--- a/lib/resolv.rb
+++ b/lib/resolv.rb
@@ -169,7 +169,7 @@ class Resolv
     begin
       raise LoadError unless /mswin|mingw|cygwin/ =~ RUBY_PLATFORM
       require 'win32/resolv'
-      DefaultFileName = Win32::Resolv.get_hosts_path
+      DefaultFileName = Win32::Resolv.get_hosts_path || IO::NULL
     rescue LoadError
       DefaultFileName = '/etc/hosts'
     end