diff --git a/libflashrom.h b/libflashrom.h
index 972e7d1..603dccf 100644
--- a/libflashrom.h
+++ b/libflashrom.h
@@ -68,7 +68,7 @@
 struct flashrom_layout;
 int flashrom_layout_read_from_ifd(struct flashrom_layout **, struct flashrom_flashctx *, const void *dump, size_t len);
 int flashrom_layout_read_fmap_from_rom(struct flashrom_layout **,
-		struct flashrom_flashctx *, off_t offset, size_t length);
+		struct flashrom_flashctx *, size_t offset, size_t length);
 int flashrom_layout_read_fmap_from_buffer(struct flashrom_layout **layout,
 		struct flashrom_flashctx *, const uint8_t *buf, size_t len);
 int flashrom_layout_include_region(struct flashrom_layout *, const char *name);