diff --git a/.github/workflows/tests.yaml b/.github/workflows/tests.yaml
index 5d96652..2c0bc73 100644
--- a/.github/workflows/tests.yaml
+++ b/.github/workflows/tests.yaml
@@ -12,7 +12,7 @@ jobs:
 
     strategy:
       matrix:
-        php-versions: [ '8.0', '8.1', '8.2', '8.3', '8.4']
+        php-versions: [ '8.1', '8.2', '8.3', '8.4', '8.5']
         dependency-version: [prefer-lowest, prefer-stable]
 
     name: PHP ${{ matrix.php-versions }} - ${{ matrix.dependency-version }}
diff --git a/composer.json b/composer.json
index 5cdd59b..ad04cb6 100644
--- a/composer.json
+++ b/composer.json
@@ -15,8 +15,8 @@
   "keywords": [ "cms", "pkcs7", "cades", "x690", "asn1", "asn.1", "ber", "der", "binary", "encoding", "decoding" ],
 
   "require": {
-    "php": ">=8.0",
-    "adapik/phpasn1": "^2.4"
+    "php": ">=8.1",
+    "adapik/phpasn1": "^2.6.0"
   },
   "require-dev": {
     "phpunit/phpunit": "^9.6"
diff --git a/src/CMS/CMSBase.php b/src/CMS/CMSBase.php
index c4f7cd9..cbeaa37 100644
--- a/src/CMS/CMSBase.php
+++ b/src/CMS/CMSBase.php
@@ -14,6 +14,7 @@
 use Adapik\CMS\Interfaces\CMSInterface;
 use FG\ASN1\ASN1Object;
 use FG\ASN1\ASN1ObjectInterface;
+use FG\ASN1\Exception\ParserException;
 use FG\ASN1\Mapper\Mapper;
 
 /**
@@ -45,7 +46,11 @@ public function __construct(ASN1ObjectInterface $object)
      */
     final protected static function makeFromContent(string $content, string $mapperClass, string $objectClass): ASN1ObjectInterface
     {
-        $object = ASN1Object::fromFile($content);
+        try {
+            $object = ASN1Object::fromFile($content);
+        } catch (ParserException $e) {
+            throw new FormatException($e->getMessage(), 0, $e);
+        }
 
         if (!$object instanceof $objectClass) {
             throw new FormatException(
diff --git a/tests/CMS/PrivateKeyTest.php b/tests/CMS/PrivateKeyTest.php
index 9de2915..46f6b60 100644
--- a/tests/CMS/PrivateKeyTest.php
+++ b/tests/CMS/PrivateKeyTest.php
@@ -61,4 +61,13 @@ public function testKeyAlgorithm()
         // RSA encryption OID is 1.2.840.113549.1.1.1
         self::assertStringContainsString('1.2.840.113549.1.1.1', $algorithm->getAlgorithmOid());
     }
+
+    public function testNonOctetStringPrivateKeyIsRejected()
+    {
+        $this->expectException(FormatException::class);
+
+        PrivateKey::createFromContent(hex2bin(
+            '3034020100300b0609608648016503040320442280203434343434343434343434343434343434343434343434343434343434343434'
+        ));
+    }
 }