diff --git a/src/Endpoints/PageRules.php b/src/Endpoints/PageRules.php
index c8be3ab..bc0bea5 100644
--- a/src/Endpoints/PageRules.php
+++ b/src/Endpoints/PageRules.php
@@ -70,19 +70,19 @@ class PageRules implements API
         string $direction = null,
         string $match = null
     ): array {
-        if (is_null($status) && !in_array($status, ['active', 'disabled'])) {
+        if ($status === null && !in_array($status, ['active', 'disabled'])) {
             throw new EndpointException('Page Rules can only be listed by status of active or disabled.');
         }
 
-        if (is_null($order) && !in_array($order, ['status', 'priority'])) {
+        if ($order === null && !in_array($order, ['status', 'priority'])) {
             throw new EndpointException('Page Rules can only be ordered by status or priority.');
         }
 
-        if (is_null($direction) && !in_array($direction, ['asc', 'desc'])) {
+        if ($direction === null && !in_array($direction, ['asc', 'desc'])) {
             throw new EndpointException('Direction of Page Rule ordering can only be asc or desc.');
         }
 
-        if (is_null($match) && !in_array($match, ['all', 'any'])) {
+        if ($match === null && !in_array($match, ['all', 'any'])) {
             throw new EndpointException('Match can only be any or all.');
         }
 
diff --git a/src/Endpoints/Zones.php b/src/Endpoints/Zones.php
index 370bae6..c06fd27 100644
--- a/src/Endpoints/Zones.php
+++ b/src/Endpoints/Zones.php
@@ -160,7 +160,7 @@ class Zones implements API
 
     public function cachePurge(string $zoneID, array $files = null, array $tags = null): bool
     {
-        if (is_null($files) && is_null($tags)) {
+        if ($files === null && $tags === null) {
             throw new EndpointException('No files or tags to purge.');
         }