diff --git a/test-tool/Makefile.am b/test-tool/Makefile.am
index ece16dd..513c387 100644
--- a/test-tool/Makefile.am
+++ b/test-tool/Makefile.am
@@ -19,6 +19,7 @@ iscsi_test_cu_SOURCES = iscsi-test-cu.c \
 	test_compareandwrite_simple.c \
 	test_compareandwrite_dpofua.c \
 	test_compareandwrite_miscompare.c \
+	test_compareandwrite_unwritten.c \
 	test_extendedcopy_simple.c \
 	test_extendedcopy_param.c \
 	test_extendedcopy_descr_limits.c \
diff --git a/test-tool/iscsi-test-cu.c b/test-tool/iscsi-test-cu.c
index f918250..764ec9d 100644
--- a/test-tool/iscsi-test-cu.c
+++ b/test-tool/iscsi-test-cu.c
@@ -75,6 +75,7 @@ static CU_TestInfo tests_compareandwrite[] = {
         { (char *)"Simple", test_compareandwrite_simple },
         { (char *)"DpoFua", test_compareandwrite_dpofua },
         { (char *)"Miscompare", test_compareandwrite_miscompare },
+        { (char *)"Unwritten", test_compareandwrite_unwritten },
         CU_TEST_INFO_NULL
 };
 
diff --git a/test-tool/iscsi-test-cu.h b/test-tool/iscsi-test-cu.h
index 4ff8860..e2a8927 100644
--- a/test-tool/iscsi-test-cu.h
+++ b/test-tool/iscsi-test-cu.h
@@ -51,6 +51,7 @@ void test_teardown(void);
 void test_compareandwrite_simple(void);
 void test_compareandwrite_dpofua(void);
 void test_compareandwrite_miscompare(void);
+void test_compareandwrite_unwritten(void);
 
 void test_extendedcopy_simple(void);
 void test_extendedcopy_param(void);
diff --git a/test-tool/test_async_abort_simple.c b/test-tool/test_async_abort_simple.c
index c7a991d..b7ed825 100644
--- a/test-tool/test_async_abort_simple.c
+++ b/test-tool/test_async_abort_simple.c
@@ -60,9 +60,13 @@ test_async_abort_cb(struct iscsi_context *iscsi __attribute__((unused)),
 		    int status, void *command_data,
 		    void *private_data)
 {
-	uint32_t tmf_response = *(uint32_t *)command_data;
+	uint32_t tmf_response;
 	struct tests_async_abort_state *state = private_data;
 
+	/* command_data NULL if a reconnect occured. see iscsi_reconnect_cb() */
+	CU_ASSERT_PTR_NOT_NULL_FATAL(command_data);
+	tmf_response = *(uint32_t *)command_data;
+
 	logging(LOG_VERBOSE, "ABORT TASK: TMF response %d for"
 		" RefCmdSN=0x%x, RefITT=0x%x",
 		tmf_response, state->wtask->cmdsn, state->wtask->itt);
diff --git a/test-tool/test_compareandwrite_unwritten.c b/test-tool/test_compareandwrite_unwritten.c
new file mode 100644
index 0000000..6bd6a2c
--- /dev/null
+++ b/test-tool/test_compareandwrite_unwritten.c
@@ -0,0 +1,78 @@
+/* -*-  mode:c; tab-width:8; c-basic-offset:8; indent-tabs-mode:nil;  -*- */
+/*
+   Copyright (C) SUSE LINUX GmbH 2016
+   Copyright (C) 2013 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 <inttypes.h>
+#include <stdlib.h>
+
+#include <CUnit/CUnit.h>
+
+#include "iscsi.h"
+#include "scsi-lowlevel.h"
+#include "iscsi-support.h"
+#include "iscsi-test-cu.h"
+
+
+void
+test_compareandwrite_unwritten(void)
+{
+	int i;
+
+	CHECK_FOR_DATALOSS;
+	CHECK_FOR_SBC;
+
+	logging(LOG_VERBOSE, LOG_BLANK_LINE);
+	logging(LOG_VERBOSE, "Test COMPARE_AND_WRITE of 1-256 blocks at the "
+		"start of the LUN, 1 block at a time");
+	for (i = 1; i < 256; i++) {
+		int caw_ret;
+		unsigned char read_buf[block_size];
+
+		/* semi-unique 'compare' buffer to trigger miscompare */
+		memset(scratch, '%', block_size);
+		memset(scratch + block_size, 'B', block_size);
+
+		caw_ret = compareandwrite(sd, i, scratch, 2 * block_size,
+				      block_size,
+				      0, 0, 0, 0,
+				      EXPECT_MISCOMPARE);
+		if (caw_ret == -2) {
+			CU_PASS("[SKIPPED] COMPARE AND WRITE not supported");
+			return;
+		}
+		READ16(sd, NULL, i, block_size,
+		       block_size, 0, 0, 0, 0, 0, read_buf,
+		       EXPECT_STATUS_GOOD);
+
+		if (caw_ret == 0) {
+			/* miscompare - confirm unwritten block doesn't match compare buf */
+			CU_ASSERT_NOT_EQUAL(memcmp(read_buf, scratch,
+						   block_size), 0);
+		} else {
+			/*
+			 * unexpected CAW success, or failure with an ASCQ that
+			 * doesn't indicate miscompare - tolerate only the
+			 * former, by checking that the range now carries data
+			 * matching the CAW write buffer.
+			 */
+			CU_ASSERT_EQUAL(memcmp(read_buf, scratch + block_size,
+					       block_size), 0);
+		}
+	}
+}