diff --git a/ext/ply/ply/yacc.py b/ext/ply/ply/yacc.py
index 3bf6e8e4d..d4bb8822d 100644
--- a/ext/ply/ply/yacc.py
+++ b/ext/ply/ply/yacc.py
@@ -68,7 +68,7 @@ __tabversion__ = "3.2"       # Table version
 # Change these to modify the default behavior of yacc (if you wish)
 #-----------------------------------------------------------------------------
 
-yaccdebug   = 1                # Debugging mode.  If set, yacc generates a
+yaccdebug   = 0                # Debugging mode.  If set, yacc generates a
                                # a 'parser.out' file in the current directory
 
 debug_file  = 'parser.out'     # Default name of the debugging file