diff --git a/bsp/simulator/SConstruct b/bsp/simulator/SConstruct
index 6724841075..b9854bb343 100755
--- a/bsp/simulator/SConstruct
+++ b/bsp/simulator/SConstruct
@@ -95,7 +95,7 @@ if GetDepend('RT_USING_MODULE'):
       dest='def',
       action='store_true',
       default=False,
-      help='create rthread.def of rtthread.dll on windows')
+      help='create rtthread.def of rtthread.dll on windows')
     if GetOption('def'):
         if rtconfig.PLATFORM == 'mingw':
             env['LINKFLAGS'] = rtconfig.DEFFILE_LFLAGS