diff --git a/src/Definition/FlagBag.php b/src/Definition/FlagBag.php
index a910664b..8c0e5c1d 100644
--- a/src/Definition/FlagBag.php
+++ b/src/Definition/FlagBag.php
@@ -17,6 +17,7 @@
 use Countable;
 use IteratorAggregate;
 use function Nelmio\Alice\deep_clone;
+use Traversable;
 
 /**
  * Collection of flags.
@@ -94,7 +95,7 @@ public function getKey(): string
         return $this->key;
     }
     
-    public function getIterator(): ArrayIterator
+    public function getIterator(): Traversable
     {
         return new ArrayIterator(array_values($this->flags));
     }
diff --git a/src/Definition/MethodCallBag.php b/src/Definition/MethodCallBag.php
index 1f80ce36..b893da6a 100644
--- a/src/Definition/MethodCallBag.php
+++ b/src/Definition/MethodCallBag.php
@@ -16,6 +16,7 @@
 use ArrayIterator;
 use Countable;
 use IteratorAggregate;
+use Traversable;
 
 final class MethodCallBag implements IteratorAggregate, Countable
 {
@@ -51,7 +52,7 @@ public function isEmpty(): bool
         return [] === $this->methodCalls;
     }
     
-    public function getIterator(): ArrayIterator
+    public function getIterator(): Traversable
     {
         return new ArrayIterator(array_values($this->methodCalls));
     }
diff --git a/src/Definition/PropertyBag.php b/src/Definition/PropertyBag.php
index 8c1dbfc7..ccf89db1 100644
--- a/src/Definition/PropertyBag.php
+++ b/src/Definition/PropertyBag.php
@@ -16,6 +16,7 @@
 use ArrayIterator;
 use Countable;
 use IteratorAggregate;
+use Traversable;
 
 final class PropertyBag implements IteratorAggregate, Countable
 {
@@ -51,7 +52,7 @@ public function isEmpty(): bool
         return [] === $this->properties;
     }
     
-    public function getIterator(): ArrayIterator
+    public function getIterator(): Traversable
     {
         return new ArrayIterator(array_values($this->properties));
     }
diff --git a/src/FixtureBag.php b/src/FixtureBag.php
index daf41852..2f877ce2 100644
--- a/src/FixtureBag.php
+++ b/src/FixtureBag.php
@@ -17,6 +17,7 @@
 use IteratorAggregate;
 use Nelmio\Alice\Throwable\Exception\FixtureNotFoundException;
 use Nelmio\Alice\Throwable\Exception\FixtureNotFoundExceptionFactory;
+use Traversable;
 
 /**
  * Value object containing a list of fixtures.
@@ -85,7 +86,7 @@ public function get(string $id): FixtureInterface
         throw FixtureNotFoundExceptionFactory::create($id);
     }
     
-    public function getIterator(): ArrayIterator
+    public function getIterator(): Traversable
     {
         return new ArrayIterator($this->fixtures);
     }
diff --git a/src/ObjectBag.php b/src/ObjectBag.php
index 6921530c..b7b5ced2 100644
--- a/src/ObjectBag.php
+++ b/src/ObjectBag.php
@@ -21,6 +21,7 @@
 use Nelmio\Alice\Throwable\Exception\InvalidArgumentExceptionFactory;
 use Nelmio\Alice\Throwable\Exception\ObjectNotFoundException;
 use Nelmio\Alice\Throwable\Exception\ObjectNotFoundExceptionFactory;
+use Traversable;
 
 /**
  * Value object containing a list of objects.
@@ -121,8 +122,8 @@ public function count(): int
     {
         return count($this->objects);
     }
-    
-    public function getIterator(): ArrayIterator
+
+    public function getIterator(): Traversable
     {
         return new ArrayIterator($this->objects);
     }
diff --git a/src/ParameterBag.php b/src/ParameterBag.php
index 544b4d86..765b9a7a 100644
--- a/src/ParameterBag.php
+++ b/src/ParameterBag.php
@@ -18,6 +18,7 @@
 use IteratorAggregate;
 use Nelmio\Alice\Throwable\Exception\ParameterNotFoundException;
 use Nelmio\Alice\Throwable\Exception\ParameterNotFoundExceptionFactory;
+use Traversable;
 
 /**
  * Value object containing a list of parameters.
@@ -78,7 +79,7 @@ public function get(string $key)
         throw ParameterNotFoundExceptionFactory::create($key);
     }
     
-    public function getIterator(): ArrayIterator
+    public function getIterator(): Traversable
     {
         return new ArrayIterator($this->parameters);
     }