diff --git a/pdu/alert.go b/pdu/alert.go
index 31b1701..927671c 100644
--- a/pdu/alert.go
+++ b/pdu/alert.go
@@ -3,4 +3,4 @@ package pdu
 type (
 	ALERT_NOTIFICATION      struct{}
 	ALERT_NOTIFICATION_RESP struct{}
-)
\ No newline at end of file
+)
diff --git a/pdu/bind.go b/pdu/bind.go
index 7a5cb97..f936f92 100644
--- a/pdu/bind.go
+++ b/pdu/bind.go
@@ -2,7 +2,7 @@ package pdu
 
 type (
 	BIND struct {
-		PDU_HEADER
+		header            PDU_HEADER
 		system_id         string
 		password          string
 		system_type       string
@@ -12,7 +12,7 @@ type (
 		address_range     string
 	}
 	BIND_RESP struct {
-		PDU_HEADER
+		header               PDU_HEADER
 		system_id            string
 		sc_interface_version uint8
 	}
@@ -34,11 +34,11 @@ type (
 	BIND_TRANSCIEVER_RESP struct {
 		BIND_RESP
 	}
-	
+
 	UNBIND struct {
 		PDU_HEADER
 	}
 	UNBIND_RESP struct {
 		PDU_HEADER
 	}
-)
\ No newline at end of file
+)
diff --git a/pdu/cancel.go b/pdu/cancel.go
index 9c2d69c..1591250 100644
--- a/pdu/cancel.go
+++ b/pdu/cancel.go
@@ -2,7 +2,7 @@ package pdu
 
 type (
 	CANCEL_SM struct {
-		PDU_HEADER
+		header           PDU_HEADER
 		service_type     string
 		message_id       string
 		source_addr_ton  uint8
@@ -13,6 +13,6 @@ type (
 		destination_addr string
 	}
 	CANCEL_SM_RESP struct {
-		PDU_HEADER
+		header PDU_HEADER
 	}
-)
\ No newline at end of file
+)
diff --git a/pdu/const.go b/pdu/const.go
index 1429198..7bcd313 100644
--- a/pdu/const.go
+++ b/pdu/const.go
@@ -156,4 +156,4 @@ var COMMAND_STATUS = struct {
 	ESME_RINVOPTPARAMVAL:  0x000000C4, // Invalid Optional Parameter Value
 	ESME_RDELIVERYFAILURE: 0x000000FE, // Delivery Failure (used for
 	ESME_RUNKNOWNERR:      0x000000FF, // Unknown Error
-}
\ No newline at end of file
+}
diff --git a/pdu/data.go b/pdu/data.go
index 2e9acb5..eafaf88 100644
--- a/pdu/data.go
+++ b/pdu/data.go
@@ -3,4 +3,4 @@ package pdu
 type (
 	DATA_SM      struct{}
 	DATA_SM_RESP struct{}
-)
\ No newline at end of file
+)
diff --git a/pdu/deliver.go b/pdu/deliver.go
index b6b3cf7..ec36b71 100644
--- a/pdu/deliver.go
+++ b/pdu/deliver.go
@@ -2,11 +2,11 @@ package pdu
 
 type (
 	DELIVER_SM struct {
-		PDU_HEADER
+		header PDU_HEADER
 		SUBMIT_SM
 	}
 	DELIVER_SM_RESP struct {
-		PDU_HEADER
+		header PDU_HEADER
 		SUBMIT_SM_RESP
 	}
-)
\ No newline at end of file
+)
diff --git a/pdu/enquire.go b/pdu/enquire.go
index 66afa09..eeec34b 100644
--- a/pdu/enquire.go
+++ b/pdu/enquire.go
@@ -2,9 +2,9 @@ package pdu
 
 type (
 	ENQUIRE_LINK struct {
-		PDU_HEADER
+		header PDU_HEADER
 	}
 	ENQUIRE_LINK_RESP struct {
-		PDU_HEADER
+		header PDU_HEADER
 	}
-)
\ No newline at end of file
+)
diff --git a/pdu/pdu.go b/pdu/pdu.go
index ba00d95..7f47104 100644
--- a/pdu/pdu.go
+++ b/pdu/pdu.go
@@ -22,7 +22,7 @@ type (
 	}
 
 	GENERIC_NACK struct {
-		PDU_HEADER
+		header PDU_HEADER
 	}
 )
 
@@ -63,4 +63,4 @@ func (p *PDU_HEADER) Decode(data []uint8) error {
 }
 func (p *PDU_HEADER) Size() uint32 {
 	return 16
-}
\ No newline at end of file
+}
diff --git a/pdu/pdu_test.go b/pdu/pdu_test.go
index 207b30f..239eb88 100644
--- a/pdu/pdu_test.go
+++ b/pdu/pdu_test.go
@@ -448,4 +448,4 @@ func TestSizeReturns16(t *testing.T) {
 	if p.Size() != 16 {
 		t.Errorf("Expected size to be 16, got %d", p.Size())
 	}
-}
\ No newline at end of file
+}
diff --git a/pdu/query.go b/pdu/query.go
index d680fa2..bd6e4e8 100644
--- a/pdu/query.go
+++ b/pdu/query.go
@@ -3,4 +3,4 @@ package pdu
 type (
 	QUERY_SM      struct{}
 	QUERY_SM_RESP struct{}
-)
\ No newline at end of file
+)
diff --git a/pdu/replace.go b/pdu/replace.go
index 115897e..2b6062e 100644
--- a/pdu/replace.go
+++ b/pdu/replace.go
@@ -3,4 +3,4 @@ package pdu
 type (
 	REPLACE_SM      struct{}
 	REPLACE_SM_RESP struct{}
-)
\ No newline at end of file
+)
diff --git a/pdu/submit.go b/pdu/submit.go
index 8e572ef..dc57ae6 100644
--- a/pdu/submit.go
+++ b/pdu/submit.go
@@ -2,7 +2,7 @@ package pdu
 
 type (
 	SUBMIT_SM struct {
-		PDU_HEADER
+		header                 PDU_HEADER
 		service_type           string
 		source_addr_ton        uint8
 		source_addr_npi        uint8
@@ -51,7 +51,7 @@ type (
 		// ussd_service_op           uint8
 	}
 	SUBMIT_SM_RESP struct {
-		PDU_HEADER
+		header     PDU_HEADER
 		message_id string
 	}
 	SUBMIT_MULTI      struct{}