diff --git a/smartie/scsi/__init__.py b/smartie/scsi/__init__.py
index 59abdd2..5fdf1a2 100644
--- a/smartie/scsi/__init__.py
+++ b/smartie/scsi/__init__.py
@@ -140,7 +140,7 @@ def identify(
 
         command16 = Command16(
             operation_code=OperationCode.COMMAND_16,
-            protocol=ATAProtocol.PIO_DATA_IN << 1,
+            protocol=ATAProtocol.PIO_DATA_IN,
             flags=CommandFlags(
                 t_length=CommandFlags.Length.IN_SECTOR_COUNT,
                 byt_blok=True,
@@ -227,7 +227,7 @@ def smart_thresholds(self) -> Tuple[SmartThresholdResponse, SCSIResponse]:
 
         command16 = Command16(
             operation_code=OperationCode.COMMAND_16,
-            protocol=ATAProtocol.PIO_DATA_IN << 1,
+            protocol=ATAProtocol.PIO_DATA_IN,
             command=ATACommands.SMART,
             flags=CommandFlags(
                 t_length=CommandFlags.Length.IN_SECTOR_COUNT,
@@ -236,7 +236,8 @@ def smart_thresholds(self) -> Tuple[SmartThresholdResponse, SCSIResponse]:
                 ck_cond=True,
             ),
             features=ATASmartFeature.SMART_READ_THRESHOLDS,
-        ).set_lba(0xC24F00)
+        )
+        command16.lba = 0xC24F00
 
         response = self.issue_command(Direction.FROM, command16, thresholds)
         return thresholds, response
@@ -249,7 +250,7 @@ def smart(self) -> Tuple[SmartDataResponse, SCSIResponse]:
 
         command16 = Command16(
             operation_code=OperationCode.COMMAND_16,
-            protocol=ATAProtocol.PIO_DATA_IN << 1,
+            protocol=ATAProtocol.PIO_DATA_IN,
             command=ATACommands.SMART,
             flags=CommandFlags(
                 t_length=CommandFlags.Length.IN_SECTOR_COUNT,
@@ -258,7 +259,8 @@ def smart(self) -> Tuple[SmartDataResponse, SCSIResponse]:
                 ck_cond=True,
             ),
             features=ATASmartFeature.SMART_READ_DATA,
-        ).set_lba(0xC24F00)
+        )
+        command16.lba = 0xC24F00
 
         response = self.issue_command(Direction.FROM, command16, smart)
         return smart, response
diff --git a/smartie/scsi/structures.py b/smartie/scsi/structures.py
index e548546..0cf5ddd 100644
--- a/smartie/scsi/structures.py
+++ b/smartie/scsi/structures.py
@@ -273,23 +273,30 @@ class Command12(ctypes.Structure):
     _pack_ = 1
     _fields_ = [
         ("operation_code", ctypes.c_ubyte),
-        ("protocol", ctypes.c_ubyte),
+        ("reserved_1", ctypes.c_ubyte, 1),
+        ("protocol", ctypes.c_ubyte, 4),
+        ("multiple_count", ctypes.c_ubyte, 3),
         ("flags", CommandFlags),
         ("features", ctypes.c_ubyte),
-        ("reserved_1", ctypes.c_ubyte, 1),
-        ("sector_count", ctypes.c_ubyte, 7),
-        ("reserved_2", ctypes.c_ubyte, 1),
-        ("lba_low", ctypes.c_ubyte, 7),
-        ("reserved_3", ctypes.c_ubyte, 1),
-        ("lba_mid", ctypes.c_ubyte, 7),
-        ("reserved_4", ctypes.c_ubyte, 1),
-        ("lba_high", ctypes.c_ubyte, 7),
+        ("sector_count", ctypes.c_ubyte),
+        ("lba_low", ctypes.c_ubyte),
+        ("lba_mid", ctypes.c_ubyte),
+        ("lba_high", ctypes.c_ubyte),
         ("device", ctypes.c_ubyte),
         ("command", ctypes.c_ubyte),
-        ("reserved_5", ctypes.c_ubyte),
+        ("reserved_2", ctypes.c_ubyte),
         ("control", ctypes.c_ubyte),
     ]
 
+    @property
+    def lba(self):
+        return self.lba_low | (self.lba_mid << 8) | (self.lba_high << 16)
+
+    @lba.setter
+    def lba(self, lba: int):
+        self.lba_low, self.lba_mid, self.lba_high = \
+            lba.to_bytes(3, byteorder="little")
+
 
 class Command16(ctypes.BigEndianStructure):
     """
@@ -304,7 +311,9 @@ class Command16(ctypes.BigEndianStructure):
     _pack_ = 1
     _fields_ = [
         ("operation_code", ctypes.c_ubyte),
-        ("protocol", ctypes.c_ubyte),
+        ("extend", ctypes.c_ubyte, 1),
+        ("protocol", ctypes.c_ubyte, 4),
+        ("multiple_count", ctypes.c_ubyte, 3),
         ("flags", CommandFlags),
         ("features", ctypes.c_ushort),
         ("sector_count", ctypes.c_ushort),
@@ -319,16 +328,22 @@ class Command16(ctypes.BigEndianStructure):
         ("control", ctypes.c_ubyte),
     ]
 
-    def set_lba(self, lba: int):
-        lba = lba.to_bytes(6, byteorder="little")
-        self.lba_high_low = lba[3]
-        self.lba_low = lba[0]
-        self.lba_high_mid = lba[4]
-        self.lba_mid = lba[1]
-        self.lba_high_high = lba[5]
-        self.lba_high = lba[2]
-
-        return self
+    @property
+    def lba(self):
+        lba = self.lba_low | (self.lba_mid << 8) | (self.lba_high << 16)
+        if not self.extend:
+            return lba
+        lba = lba | (self.lba_high_low << 24) | (self.lba_high_mid << 32) | \
+            (self.lba_high_high << 40)
+        return lba
+
+    @lba.setter
+    def lba(self, lba: int):
+        self.lba_low, self.lba_mid, self.lba_high, \
+        self.lba_high_low, self.lba_high_mid, self.lba_high_high = \
+            lba.to_bytes(6, byteorder="little")
+
+        self.extend = lba > 0xFFFFFF
 
 
 class SGIOHeader(ctypes.Structure):