diff --git a/src/Core/CHANGELOG.md b/src/Core/CHANGELOG.md
index e2f63fb50..71cd2e084 100644
--- a/src/Core/CHANGELOG.md
+++ b/src/Core/CHANGELOG.md
@@ -5,6 +5,7 @@
 ### Changed
 
 - Enable compiler optimization for the `sprintf` function.
+- Avoid calls to spl_object_ methods when computing cache key.
 
 ## 1.22.0
 
diff --git a/src/Core/src/Credentials/CacheProvider.php b/src/Core/src/Credentials/CacheProvider.php
index 428e62e47..f4a206f12 100644
--- a/src/Core/src/Credentials/CacheProvider.php
+++ b/src/Core/src/Credentials/CacheProvider.php
@@ -33,7 +33,7 @@ public function __construct(CredentialProvider $decorated)
 
     public function getCredentials(Configuration $configuration): ?Credentials
     {
-        $key = spl_object_hash($configuration);
+        $key = sha1(serialize($configuration));
         if (!\array_key_exists($key, $this->cache) || (null !== $this->cache[$key] && $this->cache[$key]->isExpired())) {
             $this->cache[$key] = $this->decorated->getCredentials($configuration);
         }
diff --git a/src/Core/src/Credentials/ChainProvider.php b/src/Core/src/Credentials/ChainProvider.php
index abc46f032..faf695e1f 100644
--- a/src/Core/src/Credentials/ChainProvider.php
+++ b/src/Core/src/Credentials/ChainProvider.php
@@ -41,7 +41,7 @@ public function __construct(iterable $providers)
 
     public function getCredentials(Configuration $configuration): ?Credentials
     {
-        $key = spl_object_hash($configuration);
+        $key = sha1(serialize($configuration));
         if (\array_key_exists($key, $this->lastSuccessfulProvider)) {
             if (null === $provider = $this->lastSuccessfulProvider[$key]) {
                 return null;