diff --git a/cores/arduino/syscalls_sam3.c b/cores/arduino/syscalls_sam3.c
index 3ea76659..6728c9e0 100644
--- a/cores/arduino/syscalls_sam3.c
+++ b/cores/arduino/syscalls_sam3.c
@@ -132,7 +132,8 @@ extern int _write( UNUSED(int file), char *ptr, int len )
 
 extern void _exit( int status )
 {
-    printf( "Exiting with status %d.\n", status ) ;
+//  printf is probably not set up by Arduino, and shouldn't be used.
+//    printf( "Exiting with status %d.\n", status ) ;
 
     for ( ; ; ) ;
 }