diff --git a/components/bt/porting/transport/driver/common/hci_driver_h4.c b/components/bt/porting/transport/driver/common/hci_driver_h4.c
index 2911289cef7..132c568e343 100644
--- a/components/bt/porting/transport/driver/common/hci_driver_h4.c
+++ b/components/bt/porting/transport/driver/common/hci_driver_h4.c
@@ -178,7 +178,7 @@ hci_h4_sm_w4_header(struct hci_h4_sm *h4sm, struct hci_h4_input_buffer *ib)
         }
 
         os_mbuf_append(h4sm->om, h4sm->hdr, h4sm->len);
-        h4sm->exp_len = (get_le16(&h4sm->hdr[2]) & 0x7fff) + 4;
+        h4sm->exp_len = (get_le16(&h4sm->hdr[2]) & 0x3fff) + 4;
         break;
     default:
         return -2;
diff --git a/components/bt/porting_btdm/transport/driver/common/hci_driver_h4.c b/components/bt/porting_btdm/transport/driver/common/hci_driver_h4.c
index c0eecf93030..76d9d7924a8 100644
--- a/components/bt/porting_btdm/transport/driver/common/hci_driver_h4.c
+++ b/components/bt/porting_btdm/transport/driver/common/hci_driver_h4.c
@@ -227,7 +227,7 @@ hci_h4_sm_w4_header(struct hci_h4_sm *h4sm, struct hci_h4_input_buffer *ib)
 #endif // !CONFIG_BT_CONTROLLER_ENABLED
 #if CONFIG_BT_LE_ISO_SUPPORT
     case HCI_H4_ISO:
-        h4sm->exp_len = (btdm_get_le16(&h4sm->hdr[2]) & 0x7fff) + 4;
+        h4sm->exp_len = (btdm_get_le16(&h4sm->hdr[2]) & 0x3fff) + 4;
         h4sm->buf = h4sm->allocs->iso(h4sm->exp_len);
         if (!h4sm->buf) {
             return -1;