diff --git a/src/InvoiceLine.php b/src/InvoiceLine.php
index e7bbddc..ea06dfb 100644
--- a/src/InvoiceLine.php
+++ b/src/InvoiceLine.php
@@ -10,6 +10,7 @@
 use function round;
 
 class InvoiceLine {
+    protected $id = null;
     protected $orderLineReference = null;
     protected $name = null;
     protected $description = null;
@@ -22,7 +23,6 @@ class InvoiceLine {
     protected $unit = "C62"; // TODO: add constants
     protected $price = null;
     protected $baseQuantity = 1;
-    protected $lineId = null;
 
     use AllowanceOrChargeTrait;
     use AttributesTrait;
@@ -31,6 +31,26 @@ class InvoiceLine {
     use PeriodTrait;
     use VatTrait;
 
+    /**
+     * Get invoice line identifier
+     * @return string|null
+     */
+    public function getId(): ?string {
+        return $this->id;
+    }
+
+
+    /**
+     * Set invoice line identifier
+     * @param  string $id Invoice line identifier
+     * @return self       Invoice line instance
+     */
+    public function setId(string $id): self {
+        $this->id = $id;
+        return $this;
+    }
+
+
     /**
      * Get order line reference
      * @return string|null Order line reference
@@ -333,22 +353,4 @@ public function getNetAmount(int $decimals=Invoice::DEFAULT_DECIMALS): ?float {
         $netAmount += $this->getChargesAmount($decimals);
         return $netAmount;
     }
-
-    /**
-     * Get Invoice line identifier
-     * @return string|null
-     */
-    public function getLineId(): ?string {
-        return $this->lineId;
-    }
-
-    /**
-     * Set Invoice line identifier
-     * @param string $lineId         The ID for the Line
-     * @return self                Invoice line instance
-     */
-    public function setLineId(string $lineId): self {
-        $this->lineId = $lineId;
-        return $this;
-    }
 }
diff --git a/src/Readers/UblReader.php b/src/Readers/UblReader.php
index 35c9234..9888e3a 100644
--- a/src/Readers/UblReader.php
+++ b/src/Readers/UblReader.php
@@ -698,10 +698,10 @@ private function parseInvoiceLine(UXML $xml, array &$taxExemptions): InvoiceLine
         $cac = UblWriter::NS_CAC;
         $cbc = UblWriter::NS_CBC;
 
-        // BT-126: Line ID
+        // BT-126: Invoice line identifier
         $lineId = $xml->get("{{$cbc}}ID");
-        if ($lineId) {
-            $line->setLineId($lineId->asText());
+        if ($lineId !== null) {
+            $line->setId($lineId->asText());
         }
 
         // BT-127: Invoice line note
diff --git a/src/Writers/UblWriter.php b/src/Writers/UblWriter.php
index d78e068..9c5d4ba 100644
--- a/src/Writers/UblWriter.php
+++ b/src/Writers/UblWriter.php
@@ -753,8 +753,8 @@ private function addDocumentTotalsNode(UXML $parent, InvoiceTotals $totals) {
     private function addLineNode(UXML $parent, InvoiceLine $line, int $index, Invoice $invoice) {
         $xml = $parent->add('cac:InvoiceLine');
 
-        // BT-126: Line ID
-        $xml->add('cbc:ID', $line->getLineId() ?? (string) $index);
+        // BT-126: Invoice line identifier
+        $xml->add('cbc:ID', $line->getId() ?? (string) $index);
 
         // BT-127: Invoice line note
         $note = $line->getNote();
diff --git a/tests/Writers/UblWriterTest.php b/tests/Writers/UblWriterTest.php
index 6a58e72..fdd9972 100644
--- a/tests/Writers/UblWriterTest.php
+++ b/tests/Writers/UblWriterTest.php
@@ -79,7 +79,7 @@ private function getSampleInvoice(): Invoice {
             ->addLine($complexLine)
             ->addLine((new InvoiceLine)->setName('Line #2')->setPrice(40, 2)->setVatRate(21)->setQuantity(4))
             ->addLine((new InvoiceLine)->setName('Line #3')->setPrice(0.56)->setVatRate(10)->setQuantity(2))
-            ->addLine((new InvoiceLine)->setLineId('5')->setName('Line #4')->setPrice(0.56)->setVatRate(10)->setQuantity(2))
+            ->addLine((new InvoiceLine)->setId('5')->setName('Line #4')->setPrice(0.56)->setVatRate(10)->setQuantity(2))
             ->addAllowance((new AllowanceOrCharge)->setReason('5% discount')->setAmount(5)->markAsPercentage()->setVatRate(21))
             ->addAttachment((new Attachment)->setId(new Identifier('INV-123', 'ABT')))
             ->addAttachment($externalAttachment)