diff --git a/tool/instruction.rb b/tool/instruction.rb
index 7ecc84b26f..30377f3251 100644
--- a/tool/instruction.rb
+++ b/tool/instruction.rb
@@ -317,10 +317,10 @@ class RubyVM
         defv  << [opes[i], e]
       }
 
-      make_insn_operand_optimiized(insn, ninsn, nopes, defv)
+      make_insn_operand_optimized(insn, ninsn, nopes, defv)
     end
 
-    def make_insn_operand_optimiized orig_insn, name, opes, defopes
+    def make_insn_operand_optimized orig_insn, name, opes, defopes
       comm = orig_insn.comm.dup
       comm[:c] = 'optimize'
       add_insn insn = Instruction.new(
diff --git a/version.h b/version.h
index 3449a6074e..ce53b842eb 100644
--- a/version.h
+++ b/version.h
@@ -1,5 +1,5 @@
 #define RUBY_VERSION "1.9.1"
-#define RUBY_PATCHLEVEL 347
+#define RUBY_PATCHLEVEL 348
 #define RUBY_VERSION_MAJOR 1
 #define RUBY_VERSION_MINOR 9
 #define RUBY_VERSION_TEENY 1