diff --git a/Makefile b/Makefile
index d460429..43c14c1 100644
--- a/Makefile
+++ b/Makefile
@@ -29,7 +29,7 @@ composer-update:
 	PHP_VERSION=$(PHP_VERSION) $(PHP) $(COMPOSER) update --no-interaction --no-progress --no-suggest --no-scripts
 
 phpstan:
-	PHP_VERSION=$(PHP_VERSION) $(PHP) vendor/bin/phpstan.phar analyse -l 7 src
+	PHP_VERSION=$(PHP_VERSION) $(PHP) vendor/bin/phpstan.phar analyse
 
 cs-fixer:
 	PHP_VERSION=$(PHP_VERSION) $(PHP) bin/php-cs-fixer.phar fix --config=.php_cs.dist -v --dry-run \
diff --git a/composer.json b/composer.json
index 19dd90e..fe53623 100644
--- a/composer.json
+++ b/composer.json
@@ -25,13 +25,13 @@
   "require": {
     "php": "^7.2",
     "beberlei/assert": "^2.9.9|~3.0",
-    "flix-tech/confluent-schema-registry-api": "~7.0",
-    "flix-tech/avro-php": "^3.0.0",
+    "flix-tech/confluent-schema-registry-api": "~7.1",
+    "flix-tech/avro-php": "^4.0.0",
     "widmogrod/php-functional": "^4.2|^5.0"
   },
   "require-dev": {
     "phpunit/phpunit": "~7.0,<8.0",
-    "phpstan/phpstan-shim": "^0.11",
+    "phpstan/phpstan": "^0.12",
     "phpbench/phpbench": "~0.9",
     "vlucas/phpdotenv": "~2.4",
     "symfony/serializer": "^3.4|^4.3"
diff --git a/phpstan.neon b/phpstan.neon
new file mode 100644
index 0000000..c7b1758
--- /dev/null
+++ b/phpstan.neon
@@ -0,0 +1,3 @@
+parameters:
+    level: 8
+    paths: [ src ]
diff --git a/src/Common.php b/src/Common.php
index bbc03bf..9ac5b8f 100644
--- a/src/Common.php
+++ b/src/Common.php
@@ -9,6 +9,10 @@
 
 const get = '\FlixTech\AvroSerializer\Common\get';
 
+/**
+ * @param mixed              $key
+ * @param array<mixed,mixed> $array
+ */
 function get($key, array $array): Maybe
 {
     return isset($array[$key])
@@ -25,6 +29,9 @@ function getter(): callable
 
 const inflectRecord = '\FlixTech\AvroSerializer\Common\inflectRecord';
 
+/**
+ * @param mixed $record
+ */
 function inflectRecord($record): Maybe
 {
     return \is_object($record)
@@ -34,6 +41,12 @@ function inflectRecord($record): Maybe
 
 const memoize = '\FlixTech\AvroSerializer\Common\memoize';
 
+/**
+ * @param array<mixed,mixed> $arguments
+ * @param string|null        $key
+ *
+ * @return mixed|null
+ */
 function memoize(callable $callback = null, array $arguments = [], $key = null)
 {
     static $storage = [];
diff --git a/src/Objects/DefaultRecordSerializerFactory.php b/src/Objects/DefaultRecordSerializerFactory.php
index 3f6e5f6..c369ec7 100644
--- a/src/Objects/DefaultRecordSerializerFactory.php
+++ b/src/Objects/DefaultRecordSerializerFactory.php
@@ -13,6 +13,9 @@
 
 final class DefaultRecordSerializerFactory
 {
+    /**
+     * @param array<string,mixed> $guzzleClientOptions
+     */
     public static function get(
         string $schemaRegistryURL,
         array $guzzleClientOptions = [],
diff --git a/src/Objects/Exceptions/Exceptions.php b/src/Objects/Exceptions/Exceptions.php
index dbc1655..0b2a96b 100644
--- a/src/Objects/Exceptions/Exceptions.php
+++ b/src/Objects/Exceptions/Exceptions.php
@@ -9,6 +9,9 @@ final class Exceptions
     public const ERROR_ENCODING = 501;
     public const ERROR_DECODING = 502;
 
+    /**
+     * @param mixed $record
+     */
     public static function forEncode($record, \AvroSchema $schema, \Exception $previous = null): AvroEncodingException
     {
         $exportedRecord = \var_export($record, true);
diff --git a/src/Objects/RecordSerializer.php b/src/Objects/RecordSerializer.php
index 6854e06..e358e75 100644
--- a/src/Objects/RecordSerializer.php
+++ b/src/Objects/RecordSerializer.php
@@ -75,6 +75,13 @@ class RecordSerializer
      */
     protected $protocolValidatorFunc;
 
+    /**
+     * RecordSerializer constructor.
+     *
+     * @param array<string,mixed> $options
+     *
+     * @throws \AvroIOException
+     */
     public function __construct(Registry $registry, array $options = [])
     {
         $this->registry = $registry;
@@ -100,11 +107,7 @@ public function __construct(Registry $registry, array $options = [])
     }
 
     /**
-     * @param string      $subject
-     * @param \AvroSchema $schema
-     * @param mixed       $record
-     *
-     * @return string
+     * @param mixed $record
      *
      * @throws \Exception
      * @throws \FlixTech\SchemaRegistryApi\Exception\SchemaRegistryException
@@ -120,9 +123,6 @@ public function encodeRecord(string $subject, AvroSchema $schema, $record): stri
     }
 
     /**
-     * @param string           $binaryMessage
-     * @param \AvroSchema|null $readersSchema
-     *
      * @return mixed
      *
      * @throws \InvalidArgumentException
@@ -150,11 +150,6 @@ public function decodeMessage(string $binaryMessage, AvroSchema $readersSchema =
     }
 
     /**
-     * @param string      $subject
-     * @param \AvroSchema $schema
-     *
-     * @return int
-     *
      * @throws \Exception
      * @throws \FlixTech\SchemaRegistryApi\Exception\SchemaRegistryException
      */
@@ -192,8 +187,6 @@ private function extractValueFromRegistryResponse($response)
     }
 
     /**
-     * @param \FlixTech\SchemaRegistryApi\Exception\SchemaRegistryException $e
-     *
      * @throws \FlixTech\SchemaRegistryApi\Exception\SchemaRegistryException
      */
     private function handleSubjectOrSchemaNotFound(SchemaRegistryException $e): void
diff --git a/src/Objects/SchemaResolverInterface.php b/src/Objects/SchemaResolverInterface.php
index a285c01..b44bf4b 100644
--- a/src/Objects/SchemaResolverInterface.php
+++ b/src/Objects/SchemaResolverInterface.php
@@ -11,6 +11,9 @@
  */
 interface SchemaResolverInterface
 {
+    /**
+     * @param mixed $record
+     */
     public function valueSchemaFor($record): AvroSchema;
 
     /**
@@ -20,8 +23,6 @@ public function valueSchemaFor($record): AvroSchema;
      * If the key schema cannot be resolved otherwise, this method should throw an `CannotResolveSchemaException`.
      *
      * @param mixed $record
-     *
-     * @return AvroSchema|null
      */
     public function keySchemaFor($record): ?AvroSchema;
 }
diff --git a/src/Objects/SchemaResolvers/ChainResolver.php b/src/Objects/SchemaResolvers/ChainResolver.php
index ab5d65a..a3351e8 100644
--- a/src/Objects/SchemaResolvers/ChainResolver.php
+++ b/src/Objects/SchemaResolvers/ChainResolver.php
@@ -29,9 +29,7 @@ public function valueSchemaFor($record): AvroSchema
             }
         }
 
-        throw new \InvalidArgumentException(
-            'No schema resolver in the chain is able to resolve the schema for the record'
-        );
+        throw new \InvalidArgumentException('No schema resolver in the chain is able to resolve the schema for the record');
     }
 
     public function keySchemaFor($record): ?AvroSchema
diff --git a/src/Objects/SchemaResolvers/DefinitionInterfaceResolver.php b/src/Objects/SchemaResolvers/DefinitionInterfaceResolver.php
index d497b61..d569147 100644
--- a/src/Objects/SchemaResolvers/DefinitionInterfaceResolver.php
+++ b/src/Objects/SchemaResolvers/DefinitionInterfaceResolver.php
@@ -14,8 +14,6 @@ class DefinitionInterfaceResolver implements SchemaResolverInterface
     /**
      * @param mixed $record
      *
-     * @return \AvroSchema
-     *
      * @throws \AvroSchemaParseException
      */
     public function valueSchemaFor($record): AvroSchema
@@ -29,8 +27,6 @@ public function valueSchemaFor($record): AvroSchema
     /**
      * @param mixed $record
      *
-     * @return \AvroSchema|null
-     *
      * @throws \AvroSchemaParseException
      */
     public function keySchemaFor($record): ?AvroSchema
@@ -46,6 +42,9 @@ public function keySchemaFor($record): ?AvroSchema
         return AvroSchema::parse($keySchemaJson);
     }
 
+    /**
+     * @param mixed $record
+     */
     private function guardRecordHasDefinition($record): void
     {
         Assert::that($record)
diff --git a/src/Protocol.php b/src/Protocol.php
index 18924bf..17ce63e 100644
--- a/src/Protocol.php
+++ b/src/Protocol.php
@@ -64,7 +64,7 @@ function decode(string $binaryString): Either
         PROTOCOL_ACCESSOR_AVRO
     );
 
-    /** @var array|bool $unpacked */
+    /** @var array<mixed,mixed>|bool $unpacked */
     $unpacked = @\unpack(
         $packedFormat,
         $binaryString
@@ -84,6 +84,9 @@ function decode(string $binaryString): Either
 
 const validate = '\FlixTech\AvroSerializer\Protocol\validate';
 
+/**
+ * @param array<mixed,mixed> $decoded
+ */
 function validate(int $protocolVersion, array $decoded): Maybe
 {
     $valid = isset($decoded[PROTOCOL_ACCESSOR_VERSION], $decoded[PROTOCOL_ACCESSOR_SCHEMA_ID], $decoded[PROTOCOL_ACCESSOR_AVRO])
@@ -98,6 +101,9 @@ function validate(int $protocolVersion, array $decoded): Maybe
 
 const validator = '\FlixTech\AvroSerializer\Protocol\validator';
 
+/**
+ * @return \Closure
+ */
 function validator(int $protocolVersion)
 {
     return curryN(2, validate)($protocolVersion);
diff --git a/src/Serialize.php b/src/Serialize.php
index 2276832..1733751 100644
--- a/src/Serialize.php
+++ b/src/Serialize.php
@@ -18,10 +18,6 @@
 const avroStringIo = '\FlixTech\AvroSerializer\Serialize\avroStringIo';
 
 /**
- * @param string $contents
- *
- * @return \AvroStringIO
- *
  * @throws \AvroIOException
  */
 function avroStringIo(string $contents): AvroStringIO
@@ -46,8 +42,6 @@ function avroBinaryDecoder(AvroStringIO $io): AvroIOBinaryDecoder
 const avroDatumWriter = '\FlixTech\AvroSerializer\Serialize\avroDatumWriter';
 
 /**
- * @return callable
- *
  * @throws \AvroIOException
  */
 function avroDatumWriter(): callable
@@ -60,6 +54,9 @@ function avroDatumWriter(): callable
 
 const writeDatum = '\FlixTech\AvroSerializer\Serialize\writeDatum';
 
+/**
+ * @param mixed $record
+ */
 function writeDatum(AvroIODatumWriter $writer, AvroStringIO $io, AvroSchema $schema, $record): Either
 {
     return tryCatch(
@@ -81,8 +78,6 @@ static function (\AvroException $e) use ($record, $schema) {
 const avroDatumReader = '\FlixTech\AvroSerializer\Serialize\avroDatumReader';
 
 /**
- * @return callable
- *
  * @throws \AvroIOException
  */
 function avroDatumReader(): callable
@@ -95,6 +90,9 @@ function avroDatumReader(): callable
 
 const readDatum = '\FlixTech\AvroSerializer\Serialize\readDatum';
 
+/**
+ * @param mixed $data
+ */
 function readDatum(
     AvroIODatumReader $reader,
     AvroStringIO $io,
diff --git a/test/Integrations/Symfony/Serializer/AvroSerDeEncoderTest.php b/test/Integrations/Symfony/Serializer/AvroSerDeEncoderTest.php
index 831a3b5..3c822a2 100644
--- a/test/Integrations/Symfony/Serializer/AvroSerDeEncoderTest.php
+++ b/test/Integrations/Symfony/Serializer/AvroSerDeEncoderTest.php
@@ -110,8 +110,6 @@ public function it_should_decode_with_valid_decode_context(): void
      * @test
      * @expectedException \InvalidArgumentException
      * @dataProvider encodeContextValidationDataProvider
-     *
-     * @param array $context
      */
     public function it_should_validate_encode_context(array $context): void
     {
diff --git a/test/Objects/RecordSerializerIntegrationTest.php b/test/Objects/RecordSerializerIntegrationTest.php
index 58984b0..3df2a00 100644
--- a/test/Objects/RecordSerializerIntegrationTest.php
+++ b/test/Objects/RecordSerializerIntegrationTest.php
@@ -36,8 +36,6 @@ public function it_encodes_valid_records(): RecordSerializer
      *
      * @expectedException \FlixTech\SchemaRegistryApi\Exception\IncompatibleAvroSchemaException
      *
-     * @param \FlixTech\AvroSerializer\Objects\RecordSerializer $serializer
-     *
      * @throws \FlixTech\SchemaRegistryApi\Exception\SchemaRegistryException
      */
     public function it_cannot_evolve_incompatible_schema(RecordSerializer $serializer): void
@@ -50,10 +48,6 @@ public function it_cannot_evolve_incompatible_schema(RecordSerializer $serialize
      *
      * @depends it_encodes_valid_records
      *
-     * @param \FlixTech\AvroSerializer\Objects\RecordSerializer $serializer
-     *
-     * @return \FlixTech\AvroSerializer\Objects\RecordSerializer
-     *
      * @throws \FlixTech\SchemaRegistryApi\Exception\SchemaRegistryException
      */
     public function it_decodes_with_readers_schema(RecordSerializer $serializer): RecordSerializer