diff --git a/tools/hci_throughput/hci.py b/tools/hci_throughput/hci.py
index 072e395e8..69b363745 100644
--- a/tools/hci_throughput/hci.py
+++ b/tools/hci_throughput/hci.py
@@ -31,6 +31,8 @@ HCI_COMMAND_PACKET = 0x01
 HCI_ACL_DATA_PACKET = 0x02
 HCI_EVENT_PACKET = 0x04
 
+L2CAP_HDR_BYTES = 4
+
 HCI_EV_CODE_DISCONN_CMP = 0x05
 HCI_EV_CODE_CMD_CMP = 0x0e
 HCI_EV_CODE_CMD_STATUS = 0x0f
diff --git a/tools/hci_throughput/hci_commands.py b/tools/hci_throughput/hci_commands.py
index 2978ab852..286f45060 100644
--- a/tools/hci_throughput/hci_commands.py
+++ b/tools/hci_throughput/hci_commands.py
@@ -422,10 +422,11 @@ class HCI_Commands():
                 hci.max_data_len.set(*struct.unpack("<BHHHH",
                                      current_ev.return_parameters))
                 logging.info(f"Suggested Max Data Len: {hci.max_data_len}")
-                if (hci.num_of_bytes_to_send > hci.max_data_len.supported_max_tx_octets - 4):
-                    logging.critical(f"Number of bytes to send: {hci.num_of_bytes_to_send}\
-                                     not supported. Closing.")
-                    raise SystemExit("Number of bytes to send not supported. Closing.")
+                if (hci.num_of_bytes_to_send > hci.max_data_len.supported_max_tx_octets - hci.L2CAP_HDR_BYTES):
+                    logging.critical(f"Number of data bytes to send + 4 bytes of L2CAP header: {hci.num_of_bytes_to_send + 4} "
+                                     f"exceeds allowed value of: {hci.max_data_len.supported_max_tx_octets}. Closing.")
+                    raise SystemExit(f"Number of data bytes to send + 4 bytes of L2CAP header: {hci.num_of_bytes_to_send + 4} "
+                                     f"exceeds allowed value of: {hci.max_data_len.supported_max_tx_octets}. Closing.")
 
                 return status()
             elif ocf == hci.OCF_LE_READ_PHY: