diff --git a/src/Passbook/Pass.php b/src/Passbook/Pass.php
index 2b1f4ba..db61d9f 100644
--- a/src/Passbook/Pass.php
+++ b/src/Passbook/Pass.php
@@ -82,14 +82,14 @@ class Pass implements PassInterface
      * @var array
      */
     protected $beacons = [];
-    
+
     /**
      * NFC where the pass is relevant.
      *
      * @var array
      */
     protected $nfc = [];
-    
+
 
     /**
      * A list of iTunes Store item identifiers (also known as Adam IDs) for the
@@ -185,8 +185,8 @@ class Pass implements PassInterface
      * @var string
      */
     protected $logoText;
-    
-    
+
+
 
     /**
      * If true, the strip image is displayed without a shine effect.
@@ -761,7 +761,7 @@ public function setAuthenticationToken($authenticationToken)
      */
     public function getAuthenticationToken()
     {
-        return $this->authenticationToken;
+        return (string) $this->authenticationToken;
     }
 
     /**
diff --git a/src/Passbook/Pass/DateField.php b/src/Passbook/Pass/DateField.php
index a764c4f..5ee23b2 100644
--- a/src/Passbook/Pass/DateField.php
+++ b/src/Passbook/Pass/DateField.php
@@ -84,7 +84,7 @@ public function setDateStyle($dateStyle)
      */
     public function getDateStyle()
     {
-        return $this->dateStyle;
+        return (string) $this->dateStyle;
     }
 
     /**
@@ -139,7 +139,7 @@ public function setTimeStyle($timeStyle)
      */
     public function getTimeStyle()
     {
-        return $this->timeStyle;
+        return (string) $this->timeStyle;
     }
 
     /**
@@ -154,4 +154,4 @@ public function setValue($value){
 
         return parent::setValue($value);
     }
-}
\ No newline at end of file
+}
diff --git a/src/Passbook/Pass/Image.php b/src/Passbook/Pass/Image.php
index a6c5824..d2ed7c0 100644
--- a/src/Passbook/Pass/Image.php
+++ b/src/Passbook/Pass/Image.php
@@ -94,6 +94,7 @@ public function getDensity()
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function getExtension()
     {
         if ($this->forceExtension) {