Warning on first compile after launching Arduino

[Dirk-]

In file included from C:\Program Files\Arduino\hardware\arduino\avr\cores\arduino\wiring_private.h:31:0,

             from C:\Program Files\Arduino\hardware\arduino\avr\cores\arduino\wiring_digital.c:26:

C:\Program Files\Arduino\hardware\arduino\avr\cores\arduino\Arduino.h:195:0: warning: "PE" redefined

#define PE 5

^

In file included from c:\program files\arduino\hardware\tools\avr\avr\include\avr\io.h:350:0,

             from C:\Program Files\Arduino\hardware\arduino\avr\cores\arduino\wiring_private.h:26,

             from C:\Program Files\Arduino\hardware\arduino\avr\cores\arduino\wiring_digital.c:26:

c:\program files\arduino\hardware\tools\avr\avr\include\avr\iom8.h:534:0: note: this is the location of the previous definition

#define PE 2

^