diff --git a/chipdrivers.h b/chipdrivers.h
index 6d5cef0..9537775 100644
--- a/chipdrivers.h
+++ b/chipdrivers.h
@@ -51,6 +51,7 @@
 int spi_nbyte_program(int addr, uint8_t *bytes, int len);
 int spi_nbyte_read(int addr, uint8_t *bytes, int len);
 int spi_read_chunked(struct flashchip *flash, uint8_t *buf, int start, int len, int chunksize);
+int spi_write_chunked(struct flashchip *flash, uint8_t *buf, int start, int len, int chunksize);
 int spi_aai_write(struct flashchip *flash, uint8_t *buf);
 
 /* 82802ab.c */