diff --git a/Makefile.am b/Makefile.am
index 91b0441..a8d5259 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -120,7 +120,8 @@ bin_iscsi_test_SOURCES = test-tool/iscsi-test.c \
 	test-tool/0386_preventallow_2_it_nexuses.c \
 	test-tool/0390_mandatory_opcodes_sbc.c \
 	\
-	test-tool/1000_cmdsn_invalid.c
+	test-tool/1000_cmdsn_invalid.c \
+	test-tool/1010_datasn_invalid.c
 
 endif
 
diff --git a/test-tool/1000_cmdsn_invalid.c b/test-tool/1000_cmdsn_invalid.c
index d1550b1..f6d0521 100644
--- a/test-tool/1000_cmdsn_invalid.c
+++ b/test-tool/1000_cmdsn_invalid.c
@@ -15,22 +15,16 @@
    along with this program; if not, see <http://www.gnu.org/licenses/>.
 */
 
-#define _GNU_SOURCE
 #include <stdio.h>
-#include <sys/syscall.h>
-#include <dlfcn.h>
-#include <sys/types.h>
 #include <arpa/inet.h>
 #include "iscsi.h"
 #include "iscsi-private.h"
 #include "scsi-lowlevel.h"
 #include "iscsi-test.h"
 
-static int (*real_iscsi_queue_pdu)(struct iscsi_context *iscsi, struct iscsi_pdu *pdu);
-
 static int change_cmdsn;
 
-int iscsi_queue_pdu(struct iscsi_context *iscsi, struct iscsi_pdu *pdu)
+static int my_iscsi_queue_pdu(struct iscsi_context *iscsi, struct iscsi_pdu *pdu)
 {
 	switch (change_cmdsn) {
 	case 1:
@@ -44,7 +38,6 @@ int iscsi_queue_pdu(struct iscsi_context *iscsi, struct iscsi_pdu *pdu)
 	}
 
 	change_cmdsn = 0;	
-	return real_iscsi_queue_pdu(iscsi, pdu);
 }
 
 static void test_cb(struct iscsi_context *iscsi _U_, int status,
@@ -73,8 +66,6 @@ int T1000_cmdsn_invalid(const char *initiator, const char *url, int data_loss, i
 	unsigned char data[512 * 256];
 	struct iscsi_async_state test_state;
 
-	real_iscsi_queue_pdu = dlsym(RTLD_NEXT, "iscsi_queue_pdu");
-
 	printf("1000_cmdsn_invalid:\n");
 	printf("==================\n");
 	if (show_info) {
@@ -128,6 +119,7 @@ int T1000_cmdsn_invalid(const char *initiator, const char *url, int data_loss, i
 
 	iscsi->use_immediate_data = ISCSI_IMMEDIATE_DATA_NO;
 	iscsi->target_max_recv_data_segment_length = 512;
+	local_iscsi_queue_pdu = my_iscsi_queue_pdu;
 
 	printf("Write 2 blocks with CMDSN > MAXCMDSN ... ");
 	change_cmdsn = 1;
@@ -200,6 +192,7 @@ test3:
 	iscsi_set_noautoreconnect(iscsi, 0);
 
 finished:
+	local_iscsi_queue_pdu = NULL;
 	iscsi_logout_sync(iscsi);
 	iscsi_destroy_context(iscsi);
 	return ret;
diff --git a/test-tool/1010_datasn_invalid.c b/test-tool/1010_datasn_invalid.c
new file mode 100644
index 0000000..7785dd0
--- /dev/null
+++ b/test-tool/1010_datasn_invalid.c
@@ -0,0 +1,157 @@
+/* 
+   Copyright (C) 2012 by Ronnie Sahlberg <ronniesahlberg@gmail.com>
+   
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <stdio.h>
+#include <arpa/inet.h>
+#include "iscsi.h"
+#include "iscsi-private.h"
+#include "scsi-lowlevel.h"
+#include "iscsi-test.h"
+
+static int clamp_datasn;
+
+static void my_iscsi_queue_pdu(struct iscsi_context *iscsi, struct iscsi_pdu *pdu)
+{
+	switch (clamp_datasn) {
+	case 1:
+		/* change datasn to 0 */
+		*(uint32_t *)&pdu->outdata.data[36] = 0;
+		break;
+	}
+}
+
+static void test_cb(struct iscsi_context *iscsi _U_, int status,
+			void *command_data _U_, void *private_data)
+{
+	struct scsi_task *task = command_data;
+	struct iscsi_async_state *state = private_data;
+
+	state->finished = 1;
+	state->status = status;
+
+	if (status) {
+		task->status = status;
+	}
+}
+
+
+int T1010_datasn_invalid(const char *initiator, const char *url, int data_loss, int show_info)
+{ 
+	struct iscsi_context *iscsi;
+	struct scsi_task *task;
+	struct scsi_readcapacity16 *rc16;
+	int ret, i, lun;
+	uint32_t block_size;
+	uint32_t num_blocks;
+	unsigned char data[512 * 256];
+	struct iscsi_async_state test_state;
+
+	printf("1010_datasn_invalid:\n");
+	printf("==================\n");
+	if (show_info) {
+		printf("Test sending commands with invalid datasn values.\n");
+		printf("1, Test that 2 DATA-IN with DATASN==0 is an error\n");
+		printf("\n");
+		return 0;
+	}
+
+	iscsi = iscsi_context_login(initiator, url, &lun);
+	if (iscsi == NULL) {
+		printf("Failed to login to target\n");
+		return -1;
+	}
+
+	/* find the size of the LUN */
+	task = iscsi_readcapacity16_sync(iscsi, lun);
+	if (task == NULL) {
+		printf("Failed to send READCAPACITY16 command: %s\n", iscsi_get_error(iscsi));
+		ret = -1;
+		goto finished;
+	}
+	if (task->status != SCSI_STATUS_GOOD) {
+		printf("READCAPACITY16 command: failed with sense. %s\n", iscsi_get_error(iscsi));
+		ret = -1;
+		scsi_free_scsi_task(task);
+		goto finished;
+	}
+	rc16 = scsi_datain_unmarshall(task);
+	if (rc16 == NULL) {
+		printf("failed to unmarshall READCAPACITY16 data. %s\n", iscsi_get_error(iscsi));
+		ret = -1;
+		scsi_free_scsi_task(task);
+		goto finished;
+	}
+	block_size = rc16->block_length;
+	num_blocks = rc16->returned_lba;
+	scsi_free_scsi_task(task);
+
+
+	if (!data_loss) {
+		printf("--dataloss flag is not set. Skipping test\n");
+		ret = -1;
+		goto finished;
+	}
+
+
+	ret = 0;
+
+	iscsi->use_immediate_data = ISCSI_IMMEDIATE_DATA_NO;
+	iscsi->target_max_recv_data_segment_length = 512;
+	local_iscsi_queue_pdu = my_iscsi_queue_pdu;
+
+	printf("Write 2 DATA-IN with DATASN == 0 ... ");
+	clamp_datasn = 1;
+	/* we dont want autoreconnect since some targets will drop the
+	 * on this condition.
+	 */
+	iscsi_set_noautoreconnect(iscsi, 1);
+
+	task = iscsi_write10_task(iscsi, lun, 0, data, 2 * block_size, block_size,
+				0, 0, 0, 0, 0,
+				test_cb, &test_state);
+	if (task == NULL) {
+	        printf("[FAILED]\n");
+		printf("Failed to send WRITE10 command: %s\n", iscsi_get_error(iscsi));
+		ret++;
+		goto test2;
+	}
+	test_state.task     = task;
+	test_state.finished = 0;
+	test_state.status   = 0;
+	wait_until_test_finished(iscsi, &test_state);
+	clamp_datasn = 0;	
+	if (task->status == SCSI_STATUS_GOOD) {
+	        printf("[FAILED]\n");
+		printf("WRITE10 command successful. Should have failed with error\n");
+		ret++;
+		scsi_free_scsi_task(task);
+		goto test2;
+	}
+	scsi_free_scsi_task(task);
+	printf("[OK]\n");
+
+
+test2:
+	/* in case the previous test failed the session */
+	iscsi_set_noautoreconnect(iscsi, 0);
+
+finished:
+	local_iscsi_queue_pdu = NULL;
+	iscsi_logout_sync(iscsi);
+	iscsi_destroy_context(iscsi);
+	return ret;
+}
diff --git a/test-tool/iscsi-test.c b/test-tool/iscsi-test.c
index 8c5f7ac..40adaf5 100644
--- a/test-tool/iscsi-test.c
+++ b/test-tool/iscsi-test.c
@@ -17,6 +17,10 @@
    along with this program; if not, see <http://www.gnu.org/licenses/>.
 */
 
+#define _GNU_SOURCE
+#include <sys/syscall.h>
+#include <dlfcn.h>
+#include <sys/types.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdint.h>
@@ -26,7 +30,7 @@
 #include <fnmatch.h>
 #include "iscsi.h"
 #include "scsi-lowlevel.h"
-#include "iscsi.h"
+#include "iscsi-private.h"
 #include "iscsi-test.h"
 
 const char *initiator = "iqn.2007-10.com.github:sahlberg:libiscsi:iscsi-test";
@@ -194,6 +198,9 @@ struct scsi_test tests[] = {
 /* invalid cmdsn from initiator */
 { "T1000_cmdsn_invalid",		T1000_cmdsn_invalid },
 
+/* invalid datasn from initiator */
+{ "T1010_datasn_invalid",		T1010_datasn_invalid },
+
 { NULL, NULL }
 };
 
@@ -304,6 +311,16 @@ void wait_until_test_finished(struct iscsi_context *iscsi, struct iscsi_async_st
 	}
 }
 
+static int (*real_iscsi_queue_pdu)(struct iscsi_context *iscsi, struct iscsi_pdu *pdu);
+
+int iscsi_queue_pdu(struct iscsi_context *iscsi, struct iscsi_pdu *pdu)
+{
+	if (local_iscsi_queue_pdu != NULL) {
+		local_iscsi_queue_pdu(iscsi, pdu);
+	}
+	return real_iscsi_queue_pdu(iscsi, pdu);
+}
+
 int main(int argc, const char *argv[])
 {
 	poptContext pc;
@@ -326,6 +343,8 @@ int main(int argc, const char *argv[])
 		POPT_TABLEEND
 	};
 
+	real_iscsi_queue_pdu = dlsym(RTLD_NEXT, "iscsi_queue_pdu");
+
 	pc = poptGetContext(argv[0], argc, argv, popt_options, POPT_CONTEXT_POSIXMEHARDER);
 	if ((res = poptGetNextOpt(pc)) < -1) {
 		fprintf(stderr, "Failed to parse option : %s %s\n",
diff --git a/test-tool/iscsi-test.h b/test-tool/iscsi-test.h
index 37fdbdc..45318b0 100644
--- a/test-tool/iscsi-test.h
+++ b/test-tool/iscsi-test.h
@@ -25,6 +25,7 @@ struct iscsi_async_state {
 	int finished;
 };
 void wait_until_test_finished(struct iscsi_context *iscsi, struct iscsi_async_state *test_state);
+void (*local_iscsi_queue_pdu)(struct iscsi_context *iscsi, struct iscsi_pdu *pdu);
 
 int T0100_read10_simple(const char *initiator, const char *url, int data_loss, int show_info);
 int T0101_read10_beyond_eol(const char *initiator, const char *url, int data_loss, int show_info);
@@ -146,3 +147,4 @@ int T0386_preventallow_2_itl_nexuses(const char *initiator, const char *url, int
 int T0390_mandatory_opcodes_sbc(const char *initiator, const char *url, int data_loss, int show_info);
 
 int T1000_cmdsn_invalid(const char *initiator, const char *url, int data_loss, int show_info);
+int T1010_datasn_invalid(const char *initiator, const char *url, int data_loss, int show_info);