diff --git a/.travis.yml b/.travis.yml
index 0d37892..7953c05 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -11,6 +11,7 @@ php:
   - 5.6
   - 7.0
   - 7.1
+  - 7.2
 
 env:
   - TEST_COMMAND="composer test-all"
diff --git a/src/Mailgun/Api/Domain.php b/src/Mailgun/Api/Domain.php
index d592142..040462b 100644
--- a/src/Mailgun/Api/Domain.php
+++ b/src/Mailgun/Api/Domain.php
@@ -83,19 +83,18 @@ class Domain extends HttpApi
      *
      * @return CreateResponse|array|ResponseInterface
      */
-    public function create($domain, $smtpPass = NULL, $spamAction = NULL, $wildcard = NULL)
+    public function create($domain, $smtpPass = null, $spamAction = null, $wildcard = null)
     {
         Assert::stringNotEmpty($domain);
-        
-        $params = ['name'] = $domain;
-        
-        // If at least smtpPass available, check for the fields spamAction wildcard
-        if(!empty($smtpPass) {
 
+        $params['name'] = $domain;
+
+        // If at least smtpPass available, check for the fields spamAction wildcard
+        if (!empty($smtpPass)) {
             // TODO(sean.johnson): Extended spam filter input validation.
             Assert::stringNotEmpty($spamAction);
             Assert::boolean($wildcard);
-            
+
             $params['smtp_password'] = $smtpPass;
             $params['spam_action'] = $spamAction;
         }