diff --git a/mrbgems/mruby-hash-ext/mrblib/hash.rb b/mrbgems/mruby-hash-ext/mrblib/hash.rb
index 11537093fc..1b73119303 100644
--- a/mrbgems/mruby-hash-ext/mrblib/hash.rb
+++ b/mrbgems/mruby-hash-ext/mrblib/hash.rb
@@ -164,7 +164,7 @@ def fetch(key, none=NONE, &block)
     unless self.key?(key)
       if block
         block.call(key)
-      elsif none != NONE
+      elsif !NONE.equal?(none)
         none
       else
         raise KeyError, "Key not found: #{key.inspect}"