diff --git a/.travis.yml b/.travis.yml
index 57bac3e..f0bdd14 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,6 +4,7 @@ php:
   - '7.1'
   - '7.2'
   - '7.3'
+  - '7.4'
 
 env:
   global:
diff --git a/tests/Functional/Infra/JsonRpcParamsValidatorTest.php b/tests/Functional/Infra/JsonRpcParamsValidatorTest.php
index 08fd841..17e706a 100644
--- a/tests/Functional/Infra/JsonRpcParamsValidatorTest.php
+++ b/tests/Functional/Infra/JsonRpcParamsValidatorTest.php
@@ -25,7 +25,7 @@ class JsonRpcParamsValidatorTest extends TestCase
     /** @var ValidatorInterface|ObjectProphecy */
     private $sfValidator;
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->sfValidator = $this->prophesize(ValidatorInterface::class);