diff --git a/programmer.h b/programmer.h
index c36b452..a22bdd2 100644
--- a/programmer.h
+++ b/programmer.h
@@ -660,6 +660,7 @@
 /* expose serialport_shutdown as it's currently used by buspirate */
 int serialport_shutdown(void *data);
 int serialport_write(unsigned char *buf, unsigned int writecnt);
+int serialport_write_nonblock(unsigned char *buf, unsigned int writecnt, unsigned int timeout, unsigned int *really_wrote);
 int serialport_read(unsigned char *buf, unsigned int readcnt);
 int serialport_read_nonblock(unsigned char *c, unsigned int readcnt, unsigned int timeout, unsigned int *really_read);