diff --git a/src/Tracing/Cache/TraceableCacheAdapterForV2.php b/src/Tracing/Cache/TraceableCacheAdapterForV2.php
index 7a5b57c9..6a0bdde5 100644
--- a/src/Tracing/Cache/TraceableCacheAdapterForV2.php
+++ b/src/Tracing/Cache/TraceableCacheAdapterForV2.php
@@ -40,7 +40,7 @@ public function __construct(HubInterface $hub, AdapterInterface $decoratedAdapte
      *
      * @return mixed
      */
-    public function get(string $key, callable $callback, float $beta = null, array &$metadata = null)
+    public function get(string $key, callable $callback, float $beta = null, array &$metadata = null): mixed
     {
         return $this->traceFunction('cache.get_item', function () use ($key, $callback, $beta, &$metadata) {
             if (!$this->decoratedAdapter instanceof CacheInterface) {
diff --git a/src/Tracing/Cache/TraceableTagAwareCacheAdapterForV2.php b/src/Tracing/Cache/TraceableTagAwareCacheAdapterForV2.php
index a89d911f..f9df4400 100644
--- a/src/Tracing/Cache/TraceableTagAwareCacheAdapterForV2.php
+++ b/src/Tracing/Cache/TraceableTagAwareCacheAdapterForV2.php
@@ -41,7 +41,7 @@ public function __construct(HubInterface $hub, TagAwareAdapterInterface $decorat
      *
      * @return mixed
      */
-    public function get(string $key, callable $callback, float $beta = null, array &$metadata = null)
+    public function get(string $key, callable $callback, float $beta = null, array &$metadata = null): mixed
     {
         return $this->traceFunction('cache.get_item', function () use ($key, $callback, $beta, &$metadata) {
             if (!$this->decoratedAdapter instanceof CacheInterface) {
diff --git a/tests/EventListener/Fixtures/UserWithoutIdentifierStub.php b/tests/EventListener/Fixtures/UserWithoutIdentifierStub.php
index b547df5d..dcc44618 100644
--- a/tests/EventListener/Fixtures/UserWithoutIdentifierStub.php
+++ b/tests/EventListener/Fixtures/UserWithoutIdentifierStub.php
@@ -31,4 +31,9 @@ public function getSalt(): ?string
     public function eraseCredentials(): void
     {
     }
+
+    public function getUserIdentifier(): string
+    {
+        return $this->getUsername();
+    }
 }