diff --git a/.gitattributes b/.gitattributes
index 3946beb0..13bb2a91 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -22,3 +22,4 @@ indocker export-ignore
 phpcs.xml export-ignore
 phpunit.xml.dist export-ignore
 phpunit-func.xml export-ignore
+phpstan.neon
diff --git a/.travis.yml b/.travis.yml
index f3606d17..6e5357c0 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -21,7 +21,7 @@ before_script:
 script:
   - mkdir build
   - composer check
-  - if [[ $TRAVIS_PHP_VERSION = 7.1 ]] || [[ $TRAVIS_PHP_VERSION = 7.2 ]]; then ~/.composer/vendor/bin/phpstan analyse module/*/src/ --level=5 -c phpstan.neon; fi
+  - if [[ $TRAVIS_PHP_VERSION = 7.1 ]] || [[ $TRAVIS_PHP_VERSION = 7.2 ]]; then ~/.composer/vendor/bin/phpstan analyse module/*/src/ --level=6 -c phpstan.neon; fi
 
 after_script:
   - vendor/bin/phpcov merge build --clover build/clover.xml
diff --git a/module/Common/src/Exception/ExceptionInterface.php b/module/Common/src/Exception/ExceptionInterface.php
index 72e53d0f..349f3f4b 100644
--- a/module/Common/src/Exception/ExceptionInterface.php
+++ b/module/Common/src/Exception/ExceptionInterface.php
@@ -3,6 +3,6 @@ declare(strict_types=1);
 
 namespace Shlinkio\Shlink\Common\Exception;
 
-interface ExceptionInterface
+interface ExceptionInterface extends \Throwable
 {
 }
diff --git a/module/Core/src/Exception/EntityDoesNotExistException.php b/module/Core/src/Exception/EntityDoesNotExistException.php
index 732eaeba..ba4d233d 100644
--- a/module/Core/src/Exception/EntityDoesNotExistException.php
+++ b/module/Core/src/Exception/EntityDoesNotExistException.php
@@ -3,9 +3,7 @@ declare(strict_types=1);
 
 namespace Shlinkio\Shlink\Core\Exception;
 
-use Shlinkio\Shlink\Common\Exception\ExceptionInterface;
-
-class EntityDoesNotExistException extends \RuntimeException implements ExceptionInterface
+class EntityDoesNotExistException extends RuntimeException
 {
     public static function createFromEntityAndConditions($entityName, array $conditions)
     {
diff --git a/module/Core/src/Exception/ExceptionInterface.php b/module/Core/src/Exception/ExceptionInterface.php
new file mode 100644
index 00000000..2901b7cb
--- /dev/null
+++ b/module/Core/src/Exception/ExceptionInterface.php
@@ -0,0 +1,8 @@
+<?php
+declare(strict_types=1);
+
+namespace Shlinkio\Shlink\Core\Exception;
+
+interface ExceptionInterface extends \Throwable
+{
+}
diff --git a/module/Core/src/Exception/InvalidArgumentException.php b/module/Core/src/Exception/InvalidArgumentException.php
new file mode 100644
index 00000000..ef3fedf9
--- /dev/null
+++ b/module/Core/src/Exception/InvalidArgumentException.php
@@ -0,0 +1,8 @@
+<?php
+declare(strict_types=1);
+
+namespace Shlinkio\Shlink\Core\Exception;
+
+class InvalidArgumentException extends \InvalidArgumentException implements ExceptionInterface
+{
+}
diff --git a/module/Core/src/Exception/InvalidShortCodeException.php b/module/Core/src/Exception/InvalidShortCodeException.php
index 03354fc0..d2201f1d 100644
--- a/module/Core/src/Exception/InvalidShortCodeException.php
+++ b/module/Core/src/Exception/InvalidShortCodeException.php
@@ -3,8 +3,6 @@ declare(strict_types=1);
 
 namespace Shlinkio\Shlink\Core\Exception;
 
-use Shlinkio\Shlink\Common\Exception\RuntimeException;
-
 class InvalidShortCodeException extends RuntimeException
 {
     public static function fromCharset($shortCode, $charSet, \Exception $previous = null)
diff --git a/module/Core/src/Exception/InvalidUrlException.php b/module/Core/src/Exception/InvalidUrlException.php
index 13e77c5d..1fa6fe19 100644
--- a/module/Core/src/Exception/InvalidUrlException.php
+++ b/module/Core/src/Exception/InvalidUrlException.php
@@ -3,8 +3,6 @@ declare(strict_types=1);
 
 namespace Shlinkio\Shlink\Core\Exception;
 
-use Shlinkio\Shlink\Common\Exception\RuntimeException;
-
 class InvalidUrlException extends RuntimeException
 {
     public static function fromUrl($url, \Throwable $previous = null)
diff --git a/module/Core/src/Exception/NonUniqueSlugException.php b/module/Core/src/Exception/NonUniqueSlugException.php
index 4f76b725..d94a61b5 100644
--- a/module/Core/src/Exception/NonUniqueSlugException.php
+++ b/module/Core/src/Exception/NonUniqueSlugException.php
@@ -3,8 +3,6 @@ declare(strict_types=1);
 
 namespace Shlinkio\Shlink\Core\Exception;
 
-use Shlinkio\Shlink\Common\Exception\InvalidArgumentException;
-
 class NonUniqueSlugException extends InvalidArgumentException
 {
     public static function fromSlug(string $slug): self
diff --git a/module/Core/src/Exception/RuntimeException.php b/module/Core/src/Exception/RuntimeException.php
new file mode 100644
index 00000000..70ee4cc5
--- /dev/null
+++ b/module/Core/src/Exception/RuntimeException.php
@@ -0,0 +1,8 @@
+<?php
+declare(strict_types=1);
+
+namespace Shlinkio\Shlink\Core\Exception;
+
+class RuntimeException extends \RuntimeException implements ExceptionInterface
+{
+}
diff --git a/module/Core/src/Service/UrlShortener.php b/module/Core/src/Service/UrlShortener.php
index 2214c144..c0e19d1e 100644
--- a/module/Core/src/Service/UrlShortener.php
+++ b/module/Core/src/Service/UrlShortener.php
@@ -11,12 +11,12 @@ use Doctrine\ORM\ORMException;
 use GuzzleHttp\ClientInterface;
 use GuzzleHttp\Exception\GuzzleException;
 use Psr\Http\Message\UriInterface;
-use Shlinkio\Shlink\Common\Exception\RuntimeException;
 use Shlinkio\Shlink\Core\Entity\ShortUrl;
 use Shlinkio\Shlink\Core\Exception\EntityDoesNotExistException;
 use Shlinkio\Shlink\Core\Exception\InvalidShortCodeException;
 use Shlinkio\Shlink\Core\Exception\InvalidUrlException;
 use Shlinkio\Shlink\Core\Exception\NonUniqueSlugException;
+use Shlinkio\Shlink\Core\Exception\RuntimeException;
 use Shlinkio\Shlink\Core\Repository\ShortUrlRepository;
 use Shlinkio\Shlink\Core\Util\TagManagerTrait;
 
diff --git a/module/Core/src/Service/UrlShortenerInterface.php b/module/Core/src/Service/UrlShortenerInterface.php
index 17859a81..9dd354d5 100644
--- a/module/Core/src/Service/UrlShortenerInterface.php
+++ b/module/Core/src/Service/UrlShortenerInterface.php
@@ -4,11 +4,11 @@ declare(strict_types=1);
 namespace Shlinkio\Shlink\Core\Service;
 
 use Psr\Http\Message\UriInterface;
-use Shlinkio\Shlink\Common\Exception\RuntimeException;
 use Shlinkio\Shlink\Core\Exception\EntityDoesNotExistException;
 use Shlinkio\Shlink\Core\Exception\InvalidShortCodeException;
 use Shlinkio\Shlink\Core\Exception\InvalidUrlException;
 use Shlinkio\Shlink\Core\Exception\NonUniqueSlugException;
+use Shlinkio\Shlink\Core\Exception\RuntimeException;
 
 interface UrlShortenerInterface
 {
diff --git a/module/Core/src/Service/VisitsTracker.php b/module/Core/src/Service/VisitsTracker.php
index 0a5cc73d..2103c04a 100644
--- a/module/Core/src/Service/VisitsTracker.php
+++ b/module/Core/src/Service/VisitsTracker.php
@@ -5,10 +5,10 @@ namespace Shlinkio\Shlink\Core\Service;
 
 use Doctrine\ORM;
 use Psr\Http\Message\ServerRequestInterface;
-use Shlinkio\Shlink\Common\Exception\InvalidArgumentException;
 use Shlinkio\Shlink\Common\Util\DateRange;
 use Shlinkio\Shlink\Core\Entity\ShortUrl;
 use Shlinkio\Shlink\Core\Entity\Visit;
+use Shlinkio\Shlink\Core\Exception\InvalidArgumentException;
 use Shlinkio\Shlink\Core\Repository\VisitRepository;
 
 class VisitsTracker implements VisitsTrackerInterface
diff --git a/module/Core/src/Service/VisitsTrackerInterface.php b/module/Core/src/Service/VisitsTrackerInterface.php
index a852c030..802983b0 100644
--- a/module/Core/src/Service/VisitsTrackerInterface.php
+++ b/module/Core/src/Service/VisitsTrackerInterface.php
@@ -4,9 +4,9 @@ declare(strict_types=1);
 namespace Shlinkio\Shlink\Core\Service;
 
 use Psr\Http\Message\ServerRequestInterface;
-use Shlinkio\Shlink\Common\Exception\InvalidArgumentException;
 use Shlinkio\Shlink\Common\Util\DateRange;
 use Shlinkio\Shlink\Core\Entity\Visit;
+use Shlinkio\Shlink\Core\Exception\InvalidArgumentException;
 
 interface VisitsTrackerInterface
 {
diff --git a/module/Core/test/Service/UrlShortenerTest.php b/module/Core/test/Service/UrlShortenerTest.php
index 5b32c49d..6f78c70c 100644
--- a/module/Core/test/Service/UrlShortenerTest.php
+++ b/module/Core/test/Service/UrlShortenerTest.php
@@ -99,7 +99,7 @@ class UrlShortenerTest extends TestCase
 
     /**
      * @test
-     * @expectedException \Shlinkio\Shlink\Common\Exception\RuntimeException
+     * @expectedException \Shlinkio\Shlink\Core\Exception\RuntimeException
      */
     public function exceptionIsThrownWhenOrmThrowsException()
     {
diff --git a/module/Rest/src/Exception/AuthenticationException.php b/module/Rest/src/Exception/AuthenticationException.php
index 36c151f3..63805483 100644
--- a/module/Rest/src/Exception/AuthenticationException.php
+++ b/module/Rest/src/Exception/AuthenticationException.php
@@ -3,9 +3,7 @@ declare(strict_types=1);
 
 namespace Shlinkio\Shlink\Rest\Exception;
 
-use Shlinkio\Shlink\Common\Exception\ExceptionInterface;
-
-class AuthenticationException extends \RuntimeException implements ExceptionInterface
+class AuthenticationException extends RuntimeException
 {
     public static function fromCredentials($username, $password)
     {
diff --git a/module/Rest/src/Exception/ExceptionInterface.php b/module/Rest/src/Exception/ExceptionInterface.php
new file mode 100644
index 00000000..45df3e09
--- /dev/null
+++ b/module/Rest/src/Exception/ExceptionInterface.php
@@ -0,0 +1,8 @@
+<?php
+declare(strict_types=1);
+
+namespace Shlinkio\Shlink\Rest\Exception;
+
+interface ExceptionInterface extends \Throwable
+{
+}
diff --git a/module/Rest/src/Exception/RuntimeException.php b/module/Rest/src/Exception/RuntimeException.php
new file mode 100644
index 00000000..e0a938ad
--- /dev/null
+++ b/module/Rest/src/Exception/RuntimeException.php
@@ -0,0 +1,8 @@
+<?php
+declare(strict_types=1);
+
+namespace Shlinkio\Shlink\Rest\Exception;
+
+class RuntimeException extends \RuntimeException implements ExceptionInterface
+{
+}
diff --git a/module/Rest/src/Middleware/BodyParserMiddleware.php b/module/Rest/src/Middleware/BodyParserMiddleware.php
index 35bfbdfa..69929af4 100644
--- a/module/Rest/src/Middleware/BodyParserMiddleware.php
+++ b/module/Rest/src/Middleware/BodyParserMiddleware.php
@@ -8,7 +8,7 @@ use Interop\Http\ServerMiddleware\DelegateInterface;
 use Interop\Http\ServerMiddleware\MiddlewareInterface;
 use Psr\Http\Message\ResponseInterface as Response;
 use Psr\Http\Message\ServerRequestInterface as Request;
-use Shlinkio\Shlink\Common\Exception\RuntimeException;
+use Shlinkio\Shlink\Rest\Exception\RuntimeException;
 
 class BodyParserMiddleware implements MiddlewareInterface, RequestMethodInterface
 {
@@ -27,7 +27,7 @@ class BodyParserMiddleware implements MiddlewareInterface, RequestMethodInterfac
         $currentParams = $request->getParsedBody();
 
         // In requests that do not allow body or if the body has already been parsed, continue to next middleware
-        if (! empty($currentParams) || in_array($method, [
+        if (! empty($currentParams) || \in_array($method, [
             self::METHOD_GET,
             self::METHOD_HEAD,
             self::METHOD_OPTIONS,
@@ -37,7 +37,7 @@ class BodyParserMiddleware implements MiddlewareInterface, RequestMethodInterfac
 
         // If the accepted content is JSON, try to parse the body from JSON
         $contentType = $this->getRequestContentType($request);
-        if (in_array($contentType, ['application/json', 'text/json', 'application/x-json'], true)) {
+        if (\in_array($contentType, ['application/json', 'text/json', 'application/x-json'], true)) {
             return $delegate->process($this->parseFromJson($request));
         }
 
@@ -48,27 +48,28 @@ class BodyParserMiddleware implements MiddlewareInterface, RequestMethodInterfac
      * @param Request $request
      * @return string
      */
-    protected function getRequestContentType(Request $request)
+    private function getRequestContentType(Request $request): string
     {
         $contentType = $request->getHeaderLine('Content-type');
-        $contentTypes = explode(';', $contentType);
-        return trim(array_shift($contentTypes));
+        $contentTypes = \explode(';', $contentType);
+        return \trim(\array_shift($contentTypes));
     }
 
     /**
      * @param Request $request
      * @return Request
+     * @throws RuntimeException
      */
-    protected function parseFromJson(Request $request)
+    private function parseFromJson(Request $request): Request
     {
         $rawBody = (string) $request->getBody();
         if (empty($rawBody)) {
             return $request;
         }
 
-        $parsedJson = json_decode($rawBody, true);
-        if (json_last_error() !== JSON_ERROR_NONE) {
-            throw new RuntimeException(sprintf('Error when parsing JSON request body: %s', json_last_error_msg()));
+        $parsedJson = \json_decode($rawBody, true);
+        if (\json_last_error() !== JSON_ERROR_NONE) {
+            throw new RuntimeException(\sprintf('Error when parsing JSON request body: %s', \json_last_error_msg()));
         }
 
         return $request->withParsedBody($parsedJson);
@@ -78,7 +79,7 @@ class BodyParserMiddleware implements MiddlewareInterface, RequestMethodInterfac
      * @param Request $request
      * @return Request
      */
-    protected function parseFromUrlEncoded(Request $request)
+    private function parseFromUrlEncoded(Request $request): Request
     {
         $rawBody = (string) $request->getBody();
         if (empty($rawBody)) {
diff --git a/module/Rest/src/Util/RestUtils.php b/module/Rest/src/Util/RestUtils.php
index dcd6632e..407b0845 100644
--- a/module/Rest/src/Util/RestUtils.php
+++ b/module/Rest/src/Util/RestUtils.php
@@ -20,7 +20,7 @@ class RestUtils
     const NOT_FOUND_ERROR = 'NOT_FOUND';
     const UNKNOWN_ERROR = 'UNKNOWN_ERROR';
 
-    public static function getRestErrorCodeFromException(Common\ExceptionInterface $e)
+    public static function getRestErrorCodeFromException(\Throwable $e)
     {
         switch (true) {
             case $e instanceof Core\InvalidShortCodeException: