diff --git a/drivers/dfu/dfu_sf.c b/drivers/dfu/dfu_sf.c
index b6d5fe2..2b26f2c 100644
--- a/drivers/dfu/dfu_sf.c
+++ b/drivers/dfu/dfu_sf.c
@@ -12,9 +12,11 @@
 #include <spi.h>
 #include <spi_flash.h>
 
-static long dfu_get_medium_size_sf(struct dfu_entity *dfu)
+static int dfu_get_medium_size_sf(struct dfu_entity *dfu, long *size)
 {
-	return dfu->data.sf.size;
+	*size = dfu->data.sf.size;
+
+	return 0;
 }
 
 static int dfu_read_medium_sf(struct dfu_entity *dfu, u64 offset, void *buf,