diff --git a/drivers/dfu/dfu_mmc.c b/drivers/dfu/dfu_mmc.c
index e2f39784005549170839f0e559300764715966bc..e7ee0770c202ea727730863fb69910b27117dbb2 100644
--- a/drivers/dfu/dfu_mmc.c
+++ b/drivers/dfu/dfu_mmc.c
@@ -98,6 +98,8 @@ static int mmc_file_op(enum dfu_mmc_op op, struct dfu_entity *dfu,
 			op == DFU_OP_READ ? "load" : "write",
 			dfu->data.mmc.dev, dfu->data.mmc.part,
 			(unsigned int) buf, dfu->name);
+		if (op == DFU_OP_WRITE)
+			sprintf(cmd_buf + strlen(cmd_buf), " %ld", *len);
 		break;
 	default:
 		printf("%s: Layout (%s) not (yet) supported!\n", __func__,