diff --git a/test/AutoDiscoverTest.php b/test/AutoDiscoverTest.php
index 3aceab95..1a88ad2a 100644
--- a/test/AutoDiscoverTest.php
+++ b/test/AutoDiscoverTest.php
@@ -122,7 +122,7 @@ public function testDocumentNodes($element = null)
             return;
         }
 
-        if (is_null($element)) {
+        if (null === $element) {
             $element = $this->dom->documentElement;
         }
 
diff --git a/test/WsdlTestHelper.php b/test/WsdlTestHelper.php
index 107f2b4c..35d2bc0c 100644
--- a/test/WsdlTestHelper.php
+++ b/test/WsdlTestHelper.php
@@ -101,7 +101,7 @@ public function testDocumentNodes($element = null)
             return;
         }
 
-        if (is_null($element)) {
+        if (null === $element) {
             $element = $this->wsdl->toDomDocument()->documentElement;
         }