diff --git a/src/Command/DeployCommand.php b/src/Command/DeployCommand.php
index 54aaf82..e3fdb08 100644
--- a/src/Command/DeployCommand.php
+++ b/src/Command/DeployCommand.php
@@ -38,7 +38,7 @@ public function __construct(FileLocator $fileLocator, string $projectDir, string
         parent::__construct();
     }
 
-    protected function configure()
+    protected function configure(): void
     {
         $this
             ->setName('deploy')
@@ -50,7 +50,7 @@ protected function configure()
         ;
     }
 
-    protected function initialize(InputInterface $input, OutputInterface $output)
+    protected function initialize(InputInterface $input, OutputInterface $output): void
     {
         $customConfigPath = $input->getOption('configuration');
         if (null !== $customConfigPath && !is_readable($customConfigPath)) {
@@ -58,12 +58,12 @@ protected function initialize(InputInterface $input, OutputInterface $output)
         }
 
         if (null !== $customConfigPath && is_readable($customConfigPath)) {
-            return $this->configFilePath = $customConfigPath;
+            $this->configFilePath = $customConfigPath;
         }
 
         $defaultConfigPath = SymfonyConfigPathGuesser::guess($this->projectDir, $input->getArgument('stage'));
         if (is_readable($defaultConfigPath)) {
-            return $this->configFilePath = $defaultConfigPath;
+            $this->configFilePath = $defaultConfigPath;
         }
 
         $this->createDefaultConfigFile($input, $output, $defaultConfigPath, $input->getArgument('stage'));
diff --git a/src/Command/RollbackCommand.php b/src/Command/RollbackCommand.php
index bf6f1f5..d6c4be5 100644
--- a/src/Command/RollbackCommand.php
+++ b/src/Command/RollbackCommand.php
@@ -33,7 +33,7 @@ public function __construct(string $projectDir, string $logDir)
         parent::__construct();
     }
 
-    protected function configure()
+    protected function configure(): void
     {
         $this
             ->setName('rollback')
@@ -45,7 +45,7 @@ protected function configure()
         ;
     }
 
-    protected function initialize(InputInterface $input, OutputInterface $output)
+    protected function initialize(InputInterface $input, OutputInterface $output): void
     {
         $customConfigPath = $input->getOption('configuration');
         if (null !== $customConfigPath && !is_readable($customConfigPath)) {
@@ -53,12 +53,12 @@ protected function initialize(InputInterface $input, OutputInterface $output)
         }
 
         if (null !== $customConfigPath && is_readable($customConfigPath)) {
-            return $this->configFilePath = $customConfigPath;
+            $this->configFilePath = $customConfigPath;
         }
 
         $defaultConfigPath = SymfonyConfigPathGuesser::guess($this->projectDir, $input->getArgument('stage'));
         if (is_readable($defaultConfigPath)) {
-            return $this->configFilePath = $defaultConfigPath;
+            $this->configFilePath = $defaultConfigPath;
         }
 
         throw new \RuntimeException(sprintf("The default configuration file does not exist or it's not readable, and no custom configuration file was given either. Create the '%s' configuration file and run this command again.", $defaultConfigPath));
diff --git a/src/DependencyInjection/EasyDeployExtension.php b/src/DependencyInjection/EasyDeployExtension.php
index 8c08e18..b52aa84 100644
--- a/src/DependencyInjection/EasyDeployExtension.php
+++ b/src/DependencyInjection/EasyDeployExtension.php
@@ -18,7 +18,7 @@
 
 class EasyDeployExtension extends Extension
 {
-    public function load(array $configs, ContainerBuilder $container)
+    public function load(array $configs, ContainerBuilder $container): void
     {
         $loader = new XmlFileLoader($container, new FileLocator(__DIR__.'/../Resources/config'));
         $loader->load('services.xml');