Index: lib/irb/init.rb
===================================================================
--- lib/irb/init.rb	(revision 35353)
+++ lib/irb/init.rb	(working copy)
@@ -115,7 +115,7 @@
 
     @CONF[:AT_EXIT] = []
 
-    @CONF[:DEBUG_LEVEL] = 1
+    @CONF[:DEBUG_LEVEL] = 0
   end
 
   def IRB.init_error
Index: lib/irb/context.rb
===================================================================
--- lib/irb/context.rb	(revision 35353)
+++ lib/irb/context.rb	(working copy)
@@ -97,7 +97,7 @@
       if @echo.nil?
 	@echo = true
       end
-      @debug_level = IRB.conf[:DEBUG_LEVEL]
+      debug_level = IRB.conf[:DEBUG_LEVEL]
     end
 
     def main
@@ -242,7 +242,6 @@
     def debug_level=(value)
       @debug_level = value
       RubyLex.debug_level = value
-      SLex.debug_level = value
     end
 
     def debug?