diff --git a/phpunit.xml b/phpunit.xml
index b749148..fa7852f 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -4,6 +4,13 @@
     colors="true"
     stopOnFailure="false"
     bootstrap="vendor/autoload.php"
+    failOnDeprecation="true"
+    failOnEmptyTestSuite="true"
+    failOnIncomplete="true"
+    failOnNotice="true"
+    failOnRisky="true"
+    failOnSkipped="false"
+    failOnWarning="true"
     xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/8.3/phpunit.xsd">
     <source>
         <include>
diff --git a/src/Descriptor/Reader.php b/src/Descriptor/Reader.php
index b8292fe..c3809fa 100644
--- a/src/Descriptor/Reader.php
+++ b/src/Descriptor/Reader.php
@@ -31,9 +31,19 @@ public function read(): ?Descriptor
         }
 
         $offset = 1;
+
+        if (!isset($bytes[$offset])) {
+            throw new Exception('Failed to read buffer entry ' . $offset);
+        }
+
         $type = $bytes[$offset];
         $offset++;
         $stdId = Buffer::getString($bytes, 5, $offset);
+
+        if (!isset($bytes[$offset])) {
+            throw new Exception('Failed to read buffer entry ' . $offset);
+        }
+
         $version = $bytes[$offset];
         $offset++;
 
diff --git a/src/Util/Buffer.php b/src/Util/Buffer.php
index c8e5687..eeb684a 100644
--- a/src/Util/Buffer.php
+++ b/src/Util/Buffer.php
@@ -4,6 +4,8 @@
 
 namespace PhpIso\Util;
 
+use PhpIso\Exception;
+
 class Buffer
 {
     /**
@@ -28,6 +30,9 @@ public static function getString(array &$buffer, int $length, int &$offset = 0,
     {
         $string = '';
         for ($i = $offset; $i < $offset + $length; $i++) {
+            if (!isset($buffer[$i])) {
+                throw new Exception('Failed to read buffer entry ' . $i);
+            }
             $string .= chr($buffer[$i]);
         }
 
@@ -68,6 +73,9 @@ public static function getBytes(array &$buffer, int $length, int &$offset = 0):
     {
         $datas = '';
         for ($i = $offset; $i < $offset + $length; $i++) {
+            if (!isset($buffer[$i])) {
+                throw new Exception('Failed to read buffer entry ' . $i);
+            }
             $datas .= $buffer[$i];
         }
 
@@ -89,6 +97,12 @@ public static function readBBO(array &$buffer, int $length, int &$offset = 0): i
         $len = $length / 2;
 
         for ($i = 0; $i < $len; $i++) {
+            if (!isset($buffer[$offset + ($len - 1 - $i)])) {
+                throw new Exception('Failed to read buffer entry ' . ($offset + ($len - 1 - $i)));
+            }
+            if (!isset($buffer[$offset + $len + $i])) {
+                throw new Exception('Failed to read buffer entry ' . ($offset + $len + $i));
+            }
             $n1 += $buffer[$offset + ($len - 1 - $i)];
             $n2 += $buffer[$offset + $len + $i];
 
@@ -115,6 +129,10 @@ public static function readLSB(array &$buffer, int $length, int &$offset = 0): i
     {
         $lsb = 0;
         for ($i = 0; $i < $length; $i++) {
+            if (!isset($buffer[$offset + ($length - 1 - $i)])) {
+                throw new Exception('Failed to read buffer entry ' . ($offset + ($length - 1 - $i)));
+            }
+
             $lsb += $buffer[$offset + $length - 1 - $i];
 
             if ($i + 1 < $length) {
@@ -135,6 +153,9 @@ public static function readMSB(array &$buffer, int $length, int &$offset = 0): i
     {
         $msb = 0;
         for ($i = 0; $i < $length; $i++) {
+            if (!isset($buffer[$offset + $i])) {
+                throw new Exception('Failed to read buffer entry ' . ($offset + $i));
+            }
             $msb += $buffer[$offset + $i];
 
             if ($i + 1 < $length) {
@@ -155,6 +176,14 @@ public static function readInt16(array &$buffer, int &$offset = 0): int
     {
         $output = 0;
 
+        if (!isset($buffer[$offset + 0])) {
+            throw new Exception('Failed to read buffer entry ' . ($offset + 0));
+        }
+
+        if (!isset($buffer[$offset + 1])) {
+            throw new Exception('Failed to read buffer entry ' . ($offset + 1));
+        }
+
         $output += $buffer[$offset + 0] << 8;
         $output += $buffer[$offset + 1];
 
@@ -171,6 +200,22 @@ public static function readInt32(array &$buffer, int &$offset = 0): int
     {
         $output = 0;
 
+        if (!isset($buffer[$offset + 0])) {
+            throw new Exception('Failed to read buffer entry ' . ($offset + 0));
+        }
+
+        if (!isset($buffer[$offset + 1])) {
+            throw new Exception('Failed to read buffer entry ' . ($offset + 1));
+        }
+
+        if (!isset($buffer[$offset + 2])) {
+            throw new Exception('Failed to read buffer entry ' . ($offset + 2));
+        }
+
+        if (!isset($buffer[$offset + 3])) {
+            throw new Exception('Failed to read buffer entry ' . ($offset + 3));
+        }
+
         $output += $buffer[$offset + 0] << 24;
         $output += $buffer[$offset + 1] << 16;
         $output += $buffer[$offset + 2] << 8;
diff --git a/tests/IsoFileTest.php b/tests/IsoFileTest.php
index 34930e3..d090eaa 100644
--- a/tests/IsoFileTest.php
+++ b/tests/IsoFileTest.php
@@ -18,13 +18,13 @@ public function testConstructorFileDoesNotExist(): void
         new IsoFile($testFile);
     }
 
-//    public function testConstructorInvalidFile(): void
-//    {
-//        $testFile = dirname(__FILE__, 2) . '/fixtures/invalid.iso';
-//
-//        $this->expectException(Exception::class);
-//        new IsoFile($testFile);
-//    }
+    public function testConstructorInvalidFile(): void
+    {
+        $testFile = dirname(__FILE__, 2) . '/fixtures/invalid.iso';
+
+        $this->expectException(Exception::class);
+        new IsoFile($testFile);
+    }
 
     public function testConstructorExistingFile(): void
     {