diff --git a/README.md b/README.md
index a3fc1e0..4d32ebd 100644
--- a/README.md
+++ b/README.md
@@ -9,3 +9,23 @@ In your project are available two new methods.
  - h4kuna\Serialize\Serialize::decode()
 
 If you enable igbinary extension, then automatic use Driver\IgBinary. Or you can define own implmentation by Driver interface. 
+
+
+## Compatibility
+
+You are using php serialize and you want to use igbinary. You can enable igbinaty on fly and old serialized data will be decoded by old php serialize.
+
+> Support compatibility, if you have serialized data by php serialize, then you can decode by IgBinary::decode() and vice versa.
+
+## Enable igbinary
+
+1. Install igbinary extension
+
+Works!
+
+## Disable igbinary
+
+1. set constant as first things `define('SERIALIZATION_FORCE_DISABLE', true);` before vendor/autoload.php
+2. wait if your all data will be decoded
+3. uninstall igbinary extension
+4. remove constant `SERIALIZATION_FORCE_DISABLE`
diff --git a/src/Driver/IgBinary.php b/src/Driver/IgBinary.php
index 36f78d1..13262a5 100644
--- a/src/Driver/IgBinary.php
+++ b/src/Driver/IgBinary.php
@@ -37,9 +37,10 @@ public static function decode(string $value)
 		$data = @igbinary_unserialize($value);
 		if ($data === null) {
 			$error = error_get_last();
+			assert($error !== null);
 			error_clear_last();
-			if ($error === null || self::serializationCheckIgbinary($value)) {
-				return null;
+			if (self::serializationCheckIgbinary($value) === false) {
+				return Php::decode($value); // fallback to native serialize
 			}
 
 			throw new InvalidStateException($error['message']);
diff --git a/src/Driver/Php.php b/src/Driver/Php.php
index c75b28d..fbf5ce4 100644
--- a/src/Driver/Php.php
+++ b/src/Driver/Php.php
@@ -28,6 +28,9 @@ public static function decode(string $value)
 				return false;
 			}
 			error_clear_last();
+			if (IgBinary::serializationCheckIgbinary($value) === true) {
+				return IgBinary::decode($value);
+			}
 
 			throw new InvalidStateException($error['message']);
 		}
diff --git a/tests/src/AutoInstallTest.php b/tests/src/AutoInstallTest.php
index 945707e..708ec9e 100644
--- a/tests/src/AutoInstallTest.php
+++ b/tests/src/AutoInstallTest.php
@@ -3,16 +3,10 @@
 namespace h4kuna\Serialize\Tests;
 
 use h4kuna\Serialize\Driver\IgBinary;
-use h4kuna\Serialize\Driver\Php;
 use h4kuna\Serialize\Serialize;
 use Tester\Assert;
 
 require_once __DIR__ . '/../bootstrap.php';
 
-if (extension_loaded('igbinary')) {
-	$data = Serialize::encode('foo');
-	Assert::same('foo', IgBinary::decode($data));
-} else {
-	$data = Serialize::encode('foo');
-	Assert::same('foo', Php::decode($data));
-}
+$data = Serialize::encode('foo');
+Assert::same('foo', IgBinary::decode($data));
diff --git a/tests/src/DisableAutoInstallTest.php b/tests/src/DisableAutoInstallTest.php
new file mode 100644
index 0000000..cd8510d
--- /dev/null
+++ b/tests/src/DisableAutoInstallTest.php
@@ -0,0 +1,14 @@
+<?php declare(strict_types=1);
+
+namespace h4kuna\Serialize\Tests;
+
+use h4kuna\Serialize\Driver\Php;
+use h4kuna\Serialize\Serialize;
+use Tester\Assert;
+
+define('SERIALIZATION_FORCE_DISABLE', true);
+
+require_once __DIR__ . '/../bootstrap.php';
+
+$data = Serialize::encode('foo');
+Assert::same('foo', Php::decode($data));
diff --git a/tests/src/Driver/IgBinaryTest.php b/tests/src/Driver/IgBinaryTest.php
index ea915fa..137de6f 100644
--- a/tests/src/Driver/IgBinaryTest.php
+++ b/tests/src/Driver/IgBinaryTest.php
@@ -2,7 +2,7 @@
 
 namespace h4kuna\Serialize\Tests\Driver;
 
-use h4kuna\Serialize\Driver\IgBinary;
+use h4kuna\Serialize\Driver;
 use Tester\Assert;
 use Tester\TestCase;
 
@@ -13,24 +13,23 @@
  */
 class IgBinaryTest extends TestCase
 {
+
 	/**
-	 * @throws \h4kuna\Serialize\Exception\InvalidStateException
+	 * @param mixed $value
+	 * @dataProvider dataBasicTypes
 	 */
-	public function testFailed(): void
+	public function testEncodeDecode($value): void
 	{
-		$value = 'foo';
-		$data = serialize($value);
-		Assert::same($value, IgBinary::decode($data));
+		Assert::same($value, Driver\IgBinary::decode(Driver\IgBinary::encode($value)));
 	}
 
-
 	/**
 	 * @param mixed $value
 	 * @dataProvider dataBasicTypes
 	 */
-	public function testForwardCompatibility($value): void
+	public function testFallback($value): void
 	{
-		Assert::same($value, IgBinary::decode(IgBinary::encode($value)));
+		Assert::same($value, Driver\IgBinary::decode(Driver\Php::encode($value)));
 	}
 
 
diff --git a/tests/src/Driver/PhpTest.php b/tests/src/Driver/PhpTest.php
index 42da2a6..cdf7b2d 100644
--- a/tests/src/Driver/PhpTest.php
+++ b/tests/src/Driver/PhpTest.php
@@ -6,8 +6,6 @@
 use Tester\Assert;
 use Tester\TestCase;
 
-define('SERIALIZATION_FORCE_DISABLE', true);
-
 require_once __DIR__ . '/../../bootstrap.php';
 
 /**
@@ -17,13 +15,12 @@ class PhpTest extends TestCase
 {
 
 	/**
-	 * @throws \h4kuna\Serialize\Exception\InvalidStateException
+	 * @param mixed $value
+	 * @dataProvider dataBasicTypes
 	 */
-	public function testBackCompatibility(): void
+	public function testFallback($value): void
 	{
-		$value = 'foo';
-		$data = Driver\IgBinary::encode($value);
-		Assert::same($value, Driver\Php::decode($data));
+		Assert::same($value, Driver\Php::decode(Driver\IgBinary::encode($value)));
 	}