diff --git a/scst/src/dev_handlers/scst_vdisk.c b/scst/src/dev_handlers/scst_vdisk.c
index ccf79030e..ee031d3a2 100644
--- a/scst/src/dev_handlers/scst_vdisk.c
+++ b/scst/src/dev_handlers/scst_vdisk.c
@@ -3201,10 +3201,10 @@ static enum compl_status_e vdisk_exec_write_same(struct vdisk_cmd_params *p)
 
 	TRACE_ENTRY();
 
-	if (unlikely(cmd->cdb[1] & 1)) {
+	if (unlikely(cmd->cdb[1] & 0x10)) {
 		TRACE_DBG("%s", "ANCHOR not supported");
 		scst_set_invalid_field_in_cdb(cmd, 1,
-			SCST_INVAL_FIELD_BIT_OFFS_VALID | 0);
+			SCST_INVAL_FIELD_BIT_OFFS_VALID | 4);
 		goto out;
 	}
 
@@ -3216,6 +3216,8 @@ static enum compl_status_e vdisk_exec_write_same(struct vdisk_cmd_params *p)
 	}
 
 	if (unlikely(cmd->data_len <= 0)) {
+		PRINT_ERROR("WRITE SAME: refused data_len = %#llx",
+			    cmd->data_len);
 		scst_set_invalid_field_in_cdb(cmd, cmd->len_off, 0);
 		goto out;
 	}
diff --git a/scst/src/scst_lib.c b/scst/src/scst_lib.c
index 1b17d3828..9c08164aa 100644
--- a/scst/src/scst_lib.c
+++ b/scst/src/scst_lib.c
@@ -7550,22 +7550,47 @@ static int get_cdb_info_lba_8_len_4(struct scst_cmd *cmd,
 	return 0;
 }
 
+static int get_cdb_info_write_same(struct scst_cmd *cmd,
+				   const struct scst_sdbops *sdbops,
+				   const bool ndob)
+{
+	const bool anchor = (cmd->cdb[1] >> 4) & 1;
+	const bool unmap  = (cmd->cdb[1] >> 3) & 1;
+
+	if (!unmap && (anchor || ndob)) {
+		PRINT_ERROR("Received invalid %s command (UNMAP = %d;"
+			    " ANCHOR = %d; NDOB = %d)",
+			    scst_get_opcode_name(cmd), unmap, anchor, ndob);
+		scst_set_invalid_field_in_cdb(cmd, 1,
+			SCST_INVAL_FIELD_BIT_OFFS_VALID | (ndob ? 0 : 4));
+		return 1;
+	}
+
+	if (ndob) {
+		cmd->bufflen = 0;
+		cmd->data_direction = SCST_DATA_NONE;
+	} else {
+		cmd->bufflen = 1;
+		cmd->data_direction = SCST_DATA_WRITE;
+	}
+
+	return 0;
+}
+
 static int get_cdb_info_write_same10(struct scst_cmd *cmd,
 	const struct scst_sdbops *sdbops)
 {
 	cmd->lba = get_unaligned_be32(cmd->cdb + sdbops->info_lba_off);
-	cmd->bufflen = 1;
 	cmd->data_len = get_unaligned_be16(cmd->cdb + sdbops->info_len_off);
-	return 0;
+	return get_cdb_info_write_same(cmd, sdbops, false);
 }
 
 static int get_cdb_info_write_same16(struct scst_cmd *cmd,
 	const struct scst_sdbops *sdbops)
 {
 	cmd->lba = get_unaligned_be64(cmd->cdb + sdbops->info_lba_off);
-	cmd->bufflen = 1;
 	cmd->data_len = get_unaligned_be32(cmd->cdb + sdbops->info_len_off);
-	return 0;
+	return get_cdb_info_write_same(cmd, sdbops, cmd->cdb[1] & 1 /*NDOB*/);
 }
 
 static int get_cdb_info_compare_and_write(struct scst_cmd *cmd,