diff --git a/tests/XML/ds/SPKIDataTest.php b/tests/XML/ds/SPKIDataTest.php
index 0637897f..b08b25d9 100644
--- a/tests/XML/ds/SPKIDataTest.php
+++ b/tests/XML/ds/SPKIDataTest.php
@@ -55,11 +55,13 @@ public function testMarshalling(): void
         $SPKISexp2 = new SPKISexp('GpM7');
         $SPKISexp3 = new SPKISexp('GpM8');
         $carriedKeyName = new CarriedKeyName('Some label');
+        $SPKISexp4 = new SPKISexp('GpM9');
 
         $SPKIData = new SPKIData([
             [$SPKISexp1, $seed],
             [$SPKISexp2, null],
             [$SPKISexp3, $carriedKeyName],
+            [$SPKISexp4, null],
         ]);
 
         $this->assertEquals(
diff --git a/tests/resources/xml/ds_SPKIData.xml b/tests/resources/xml/ds_SPKIData.xml
index ef4af6ca..21d6063a 100644
--- a/tests/resources/xml/ds_SPKIData.xml
+++ b/tests/resources/xml/ds_SPKIData.xml
@@ -4,4 +4,5 @@
   <ds:SPKISexp>GpM7</ds:SPKISexp>
   <ds:SPKISexp>GpM8</ds:SPKISexp>
   <xenc:CarriedKeyName xmlns:xenc="http://www.w3.org/2001/04/xmlenc#">Some label</xenc:CarriedKeyName>
+  <ds:SPKISexp>GpM9</ds:SPKISexp>
 </ds:SPKIData>