diff --git a/lib/StripeObject.php b/lib/StripeObject.php
index 9482a0e97b..8e9eb93c11 100644
--- a/lib/StripeObject.php
+++ b/lib/StripeObject.php
@@ -218,7 +218,9 @@ public function offsetGet($k)
         return \array_key_exists($k, $this->_values) ? $this->_values[$k] : null;
     }
 
-    // Countable method
+    /**
+     * @return int
+     */
     #[\ReturnTypeWillChange]
     public function count()
     {
@@ -424,6 +426,9 @@ public function serializeParamsValue($value, $original, $unsaved, $force, $key =
         }
     }
 
+    /**
+     * @return mixed
+     */
     #[\ReturnTypeWillChange]
     public function jsonSerialize()
     {
diff --git a/lib/Util/CaseInsensitiveArray.php b/lib/Util/CaseInsensitiveArray.php
index 9f11dc69ef..988a8255ef 100644
--- a/lib/Util/CaseInsensitiveArray.php
+++ b/lib/Util/CaseInsensitiveArray.php
@@ -33,6 +33,9 @@ public function getIterator()
         return new \ArrayIterator($this->container);
     }
 
+    /**
+     * @return void
+     */
     #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
@@ -44,6 +47,9 @@ public function offsetSet($offset, $value)
         }
     }
 
+    /**
+     * @return
+     */
     #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
@@ -52,6 +58,9 @@ public function offsetExists($offset)
         return isset($this->container[$offset]);
     }
 
+    /**
+     * @return void
+     */
     #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
@@ -59,6 +68,9 @@ public function offsetUnset($offset)
         unset($this->container[$offset]);
     }
 
+    /**
+     * @return mixed
+     */
     #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {