diff --git a/pdu/bind.go b/pdu/bind.go
index ebf3643..e7c4d90 100644
--- a/pdu/bind.go
+++ b/pdu/bind.go
@@ -2,7 +2,7 @@ package pdu
 
 type (
 	BIND struct {
-		header            PDU_HEADER
+		header            *PDU_HEADER
 		system_id         string
 		password          string
 		system_type       string
@@ -12,7 +12,7 @@ type (
 		address_range     string
 	}
 	BIND_RESP struct {
-		header               PDU_HEADER
+		header               *PDU_HEADER
 		system_id            string
 		sc_interface_version byte
 	}
@@ -36,9 +36,9 @@ type (
 	}
 
 	UNBIND struct {
-		PDU_HEADER
+		header *PDU_HEADER
 	}
 	UNBIND_RESP struct {
-		PDU_HEADER
+		header *PDU_HEADER
 	}
 )
diff --git a/pdu/cancel.go b/pdu/cancel.go
index a6f1366..723ca65 100644
--- a/pdu/cancel.go
+++ b/pdu/cancel.go
@@ -2,7 +2,7 @@ package pdu
 
 type (
 	CANCEL_SM struct {
-		header           PDU_HEADER
+		header           *PDU_HEADER
 		service_type     string
 		message_id       string
 		source_addr_ton  byte
@@ -13,6 +13,6 @@ type (
 		destination_addr string
 	}
 	CANCEL_SM_RESP struct {
-		header PDU_HEADER
+		header *PDU_HEADER
 	}
 )
diff --git a/pdu/deliver.go b/pdu/deliver.go
index ec36b71..277559b 100644
--- a/pdu/deliver.go
+++ b/pdu/deliver.go
@@ -2,11 +2,11 @@ package pdu
 
 type (
 	DELIVER_SM struct {
-		header PDU_HEADER
+		header *PDU_HEADER
 		SUBMIT_SM
 	}
 	DELIVER_SM_RESP struct {
-		header PDU_HEADER
+		header *PDU_HEADER
 		SUBMIT_SM_RESP
 	}
 )
diff --git a/pdu/enquire.go b/pdu/enquire.go
index eeec34b..a462dc8 100644
--- a/pdu/enquire.go
+++ b/pdu/enquire.go
@@ -2,9 +2,9 @@ package pdu
 
 type (
 	ENQUIRE_LINK struct {
-		header PDU_HEADER
+		header *PDU_HEADER
 	}
 	ENQUIRE_LINK_RESP struct {
-		header PDU_HEADER
+		header *PDU_HEADER
 	}
 )
diff --git a/pdu/pdu.go b/pdu/pdu.go
index 650603f..2511a1e 100644
--- a/pdu/pdu.go
+++ b/pdu/pdu.go
@@ -22,7 +22,7 @@ type (
 	}
 
 	GENERIC_NACK struct {
-		header PDU_HEADER
+		header *PDU_HEADER
 	}
 )
 
diff --git a/pdu/submit.go b/pdu/submit.go
index 1772381..a2b8c9e 100644
--- a/pdu/submit.go
+++ b/pdu/submit.go
@@ -9,7 +9,7 @@ import (
 
 type (
 	SUBMIT_SM struct {
-		header                 PDU_HEADER
+		header                 *PDU_HEADER
 		service_type           string
 		source_addr_ton        byte
 		source_addr_npi        byte
@@ -58,7 +58,7 @@ type (
 		// ussd_service_op           byte
 	}
 	SUBMIT_SM_RESP struct {
-		header     PDU_HEADER
+		header     *PDU_HEADER
 		message_id string
 	}
 	SUBMIT_MULTI      struct{}