diff --git a/include/iscsi-private.h b/include/iscsi-private.h
index a96caae..8ace255 100644
--- a/include/iscsi-private.h
+++ b/include/iscsi-private.h
@@ -43,8 +43,8 @@ extern "C" {
 #define ISCSI_RAW_HEADER_SIZE			48
 #define ISCSI_DIGEST_SIZE			 4
 
-#define ISCSI_HEADER_SIZE (ISCSI_RAW_HEADER_SIZE	\
-  + (iscsi->header_digest == ISCSI_HEADER_DIGEST_NONE?0:ISCSI_DIGEST_SIZE))
+#define ISCSI_HEADER_SIZE(hdr_digest) (ISCSI_RAW_HEADER_SIZE	\
+  + (hdr_digest == ISCSI_HEADER_DIGEST_NONE?0:ISCSI_DIGEST_SIZE))
 
 #define SMALL_ALLOC_MAX_FREE (128) /* must be power of 2 */
 
diff --git a/lib/pdu.c b/lib/pdu.c
index 441efa7..043aa75 100644
--- a/lib/pdu.c
+++ b/lib/pdu.c
@@ -111,7 +111,7 @@ iscsi_allocate_pdu(struct iscsi_context *iscsi, enum iscsi_opcode opcode,
 		return NULL;
 	}
 
-	pdu->outdata.size = ISCSI_HEADER_SIZE;
+	pdu->outdata.size = ISCSI_HEADER_SIZE(iscsi->header_digest);
 	pdu->outdata.data = iscsi_szmalloc(iscsi, pdu->outdata.size);
 
 	if (pdu->outdata.data == NULL) {
@@ -236,7 +236,7 @@ iscsi_pdu_add_data(struct iscsi_context *iscsi, struct iscsi_pdu *pdu,
 
 	/* update data segment length */
 	scsi_set_uint32(&pdu->outdata.data[4], pdu->outdata.size
-					       - ISCSI_HEADER_SIZE);
+				- ISCSI_HEADER_SIZE(iscsi->header_digest));
 
 	return 0;
 }
diff --git a/lib/socket.c b/lib/socket.c
index dd6dbb6..42db72b 100644
--- a/lib/socket.c
+++ b/lib/socket.c
@@ -599,7 +599,7 @@ iscsi_read_from_socket(struct iscsi_context *iscsi)
 	ssize_t hdr_size, data_size, count, padding_size;
 
 	do {
-		hdr_size = ISCSI_HEADER_SIZE;
+		hdr_size = ISCSI_HEADER_SIZE(iscsi->header_digest);
 		if (iscsi->incoming == NULL) {
 			iscsi->incoming = iscsi_szmalloc(iscsi, sizeof(struct iscsi_in_pdu));
 			if (iscsi->incoming == NULL) {