diff --git a/include/iscsi.h b/include/iscsi.h
index 2c2c720..26b1d24 100644
--- a/include/iscsi.h
+++ b/include/iscsi.h
@@ -573,7 +573,7 @@ iscsi_task_mgmt_target_cold_reset_async(struct iscsi_context *iscsi,
  */
 
 struct iscsi_data {
-       int size;
+       size_t size;
        unsigned char *data;
 };
 
diff --git a/lib/socket.c b/lib/socket.c
index c30f862..54d6234 100644
--- a/lib/socket.c
+++ b/lib/socket.c
@@ -753,8 +753,8 @@ iscsi_queue_pdu(struct iscsi_context *iscsi, struct iscsi_pdu *pdu)
 		unsigned long crc;
 
 		if (pdu->outdata.size < ISCSI_RAW_HEADER_SIZE + 4) {
-			iscsi_set_error(iscsi, "PDU too small (%d) to contain header digest",
-					pdu->outdata.size);
+			iscsi_set_error(iscsi, "PDU too small (%u) to contain header digest",
+					(unsigned int) pdu->outdata.size);
 			return -1;
 		}