diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5271aeb..160c361 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,11 +7,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+* [PR-5](https://github.com/OS2web/os2web_key/pull/5)
+  Convert certificates when necessary.
 * [PR-4](https://github.com/OS2web/os2web_key/pull/4)
-  Added HashiCorp Vault key provider
+  Added HashiCorp Vault key provider.
 * [PR-2](https://github.com/OS2web/os2web_key/pull/2)
-  Updated documentation
+  Updated documentation.
 * [PR-1](https://github.com/OS2web/os2web_key/pull/1)
-  Added OS2Web key module
+  Added OS2Web key module.
 
 [Unreleased]: https://github.com/rimi-itk/os2web_key
diff --git a/src/KeyHelper.php b/src/KeyHelper.php
index c25658b..54b63db 100644
--- a/src/KeyHelper.php
+++ b/src/KeyHelper.php
@@ -38,8 +38,15 @@ public function getCertificates(KeyInterface $key): array {
       throw $this->createSslRuntimeException(sprintf('Invalid key type: %s', $type::class), $key);
     }
 
-    return $this->parseCertificates($key->getKeyValue(), $type->getInputFormat(), $type->getPassphrase(), $key);
+    // Check whether conversion is needed.
+    if ($type->getInputFormat() === $type->getOutputFormat()) {
+      return $this->parseCertificates($key->getKeyValue(), $type->getInputFormat(), $type->getPassphrase(), $key);
+    }
+
+    $parsedCertificates = $this->parseCertificates($key->getKeyValue(), $type->getInputFormat(), $type->getPassphrase(), $key);
+    $convertedCertificates = $this->convertCertificates($parsedCertificates, $type->getOutputFormat(), $key);
 
+    return $this->parseCertificates($convertedCertificates, $type->getOutputFormat(), $type->getPassphrase(), $key);
   }
 
   /**