diff --git a/src/pocketmine/wizard/SetupWizard.php b/src/pocketmine/wizard/SetupWizard.php
index c650913037..8b66ed8113 100644
--- a/src/pocketmine/wizard/SetupWizard.php
+++ b/src/pocketmine/wizard/SetupWizard.php
@@ -128,13 +128,13 @@ LICENSE;
 		return true;
 	}
 
-	private function welcome(){
+	private function welcome() : void{
 		$this->message($this->lang->get("setting_up_server_now"));
 		$this->message($this->lang->get("default_values_info"));
 		$this->message($this->lang->get("server_properties"));
 	}
 
-	private function generateBaseConfig(){
+	private function generateBaseConfig() : void{
 		$config = new Config(\pocketmine\DATA . "server.properties", Config::PROPERTIES);
 
 		$config->set("motd", ($name = $this->getInput($this->lang->get("name_your_server"), self::DEFAULT_NAME)));
@@ -173,7 +173,7 @@ LICENSE;
 		$config->save();
 	}
 
-	private function generateUserFiles(){
+	private function generateUserFiles() : void{
 		$this->message($this->lang->get("op_info"));
 
 		$op = strtolower($this->getInput($this->lang->get("op_who"), ""));
@@ -197,7 +197,7 @@ LICENSE;
 		$config->save();
 	}
 
-	private function networkFunctions(){
+	private function networkFunctions() : void{
 		$config = new Config(\pocketmine\DATA . "server.properties", Config::PROPERTIES);
 		$this->error($this->lang->get("query_warning1"));
 		$this->error($this->lang->get("query_warning2"));
@@ -237,7 +237,7 @@ LICENSE;
 		$this->readLine();
 	}
 
-	private function endWizard(){
+	private function endWizard() : void{
 		$this->message($this->lang->get("you_have_finished"));
 		$this->message($this->lang->get("pocketmine_plugins"));
 		$this->message($this->lang->translateString("pocketmine_will_start", [\pocketmine\NAME]));
@@ -248,7 +248,7 @@ LICENSE;
 		sleep(4);
 	}
 
-	private function writeLine(string $line = ""){
+	private function writeLine(string $line = "") : void{
 		echo $line . PHP_EOL;
 	}
 
@@ -256,11 +256,11 @@ LICENSE;
 		return trim((string) fgets(STDIN));
 	}
 
-	private function message(string $message){
+	private function message(string $message) : void{
 		$this->writeLine("[*] " . $message);
 	}
 
-	private function error(string $message){
+	private function error(string $message) : void{
 		$this->writeLine("[!] " . $message);
 	}