diff --git a/src/pocketmine/command/CommandReader.php b/src/pocketmine/command/CommandReader.php
index 656d82464..5a779b48c 100644
--- a/src/pocketmine/command/CommandReader.php
+++ b/src/pocketmine/command/CommandReader.php
@@ -68,7 +68,7 @@ class CommandReader extends Thread{
 
 		$opts = getopt("", ["disable-readline", "enable-readline"]);
 
-		if(extension_loaded("readline") and (Utils::getOS() === "win" ? isset($opts["enable-readline"]) : !isset($opts["disable-readline"])) and !$this->isPipe(STDIN)){
+		if(extension_loaded("readline") and (Utils::getOS() === Utils::OS_WINDOWS ? isset($opts["enable-readline"]) : !isset($opts["disable-readline"])) and !$this->isPipe(STDIN)){
 			$this->type = self::TYPE_READLINE;
 		}
 	}
diff --git a/src/pocketmine/network/upnp/UPnP.php b/src/pocketmine/network/upnp/UPnP.php
index 243300879..6fe5a6951 100644
--- a/src/pocketmine/network/upnp/UPnP.php
+++ b/src/pocketmine/network/upnp/UPnP.php
@@ -37,7 +37,7 @@ abstract class UPnP{
 		if(!Internet::$online){
 			throw new \RuntimeException("Server is offline");
 		}
-		if(Utils::getOS() !== "win"){
+		if(Utils::getOS() !== Utils::OS_WINDOWS){
 			throw new \RuntimeException("UPnP is only supported on Windows");
 		}
 		if(!class_exists("COM")){
@@ -62,7 +62,7 @@ abstract class UPnP{
 		if(!Internet::$online){
 			return false;
 		}
-		if(Utils::getOS() != "win" or !class_exists("COM")){
+		if(Utils::getOS() !== Utils::OS_WINDOWS or !class_exists("COM")){
 			return false;
 		}
 
diff --git a/src/pocketmine/utils/Process.php b/src/pocketmine/utils/Process.php
index 37fa63cbe..aacdd4c33 100644
--- a/src/pocketmine/utils/Process.php
+++ b/src/pocketmine/utils/Process.php
@@ -54,7 +54,7 @@ final class Process{
 		$reserved = memory_get_usage();
 		$VmSize = null;
 		$VmRSS = null;
-		if(Utils::getOS() === "linux" or Utils::getOS() === "android"){
+		if(Utils::getOS() === Utils::OS_LINUX or Utils::getOS() === Utils::OS_ANDROID){
 			$status = @file_get_contents("/proc/self/status");
 			if($status === false) throw new AssumptionFailedError("/proc/self/status should always be accessible");
 
@@ -92,7 +92,7 @@ final class Process{
 		$stack = 0;
 		$heap = 0;
 
-		if(Utils::getOS() === "linux" or Utils::getOS() === "android"){
+		if(Utils::getOS() === Utils::OS_LINUX or Utils::getOS() === Utils::OS_ANDROID){
 			$mappings = @file("/proc/self/maps");
 			if($mappings === false) throw new AssumptionFailedError("/proc/self/maps should always be accessible");
 			foreach($mappings as $line){
@@ -110,7 +110,7 @@ final class Process{
 	}
 
 	public static function getThreadCount() : int{
-		if(Utils::getOS() === "linux" or Utils::getOS() === "android"){
+		if(Utils::getOS() === Utils::OS_LINUX or Utils::getOS() === Utils::OS_ANDROID){
 			$status = @file_get_contents("/proc/self/status");
 			if($status === false) throw new AssumptionFailedError("/proc/self/status should always be accessible");
 			if(preg_match("/Threads:[ \t]+([0-9]+)/", $status, $matches) > 0){
@@ -131,11 +131,11 @@ final class Process{
 			MainLogger::getLogger()->syncFlushBuffer();
 		}
 		switch(Utils::getOS()){
-			case "win":
+			case Utils::OS_WINDOWS:
 				exec("taskkill.exe /F /PID $pid > NUL");
 				break;
-			case "mac":
-			case "linux":
+			case Utils::OS_MACOS:
+			case Utils::OS_LINUX:
 			default:
 				if(function_exists("posix_kill")){
 					posix_kill($pid, 9); //SIGKILL
diff --git a/src/pocketmine/utils/Terminal.php b/src/pocketmine/utils/Terminal.php
index 22071cf23..9485acc9b 100644
--- a/src/pocketmine/utils/Terminal.php
+++ b/src/pocketmine/utils/Terminal.php
@@ -182,14 +182,14 @@ abstract class Terminal{
 		}
 
 		switch(Utils::getOS()){
-			case "linux":
-			case "mac":
-			case "bsd":
+			case Utils::OS_LINUX:
+			case Utils::OS_MACOS:
+			case Utils::OS_BSD:
 				self::getEscapeCodes();
 				return;
 
-			case "win":
-			case "android":
+			case Utils::OS_WINDOWS:
+			case Utils::OS_ANDROID:
 				self::getFallbackEscapeCodes();
 				return;
 		}
diff --git a/src/pocketmine/utils/Timezone.php b/src/pocketmine/utils/Timezone.php
index 8e12d66a2..4c7e29c1d 100644
--- a/src/pocketmine/utils/Timezone.php
+++ b/src/pocketmine/utils/Timezone.php
@@ -113,7 +113,7 @@ abstract class Timezone{
 	 */
 	public static function detectSystemTimezone(){
 		switch(Utils::getOS()){
-			case 'win':
+			case Utils::OS_WINDOWS:
 				$regex = '/(UTC)(\+*\-*\d*\d*\:*\d*\d*)/';
 
 				/*
@@ -148,7 +148,7 @@ abstract class Timezone{
 				}
 
 				return self::parseOffset($offset);
-			case 'linux':
+			case Utils::OS_LINUX:
 				// Ubuntu / Debian.
 				$data = @file_get_contents('/etc/timezone');
 				if($data !== false){
@@ -170,7 +170,7 @@ abstract class Timezone{
 				}
 
 				return self::parseOffset($offset);
-			case 'mac':
+			case Utils::OS_MACOS:
 				$filename = @readlink('/etc/localtime');
 				if($filename !== false and strpos($filename, '/usr/share/zoneinfo/') === 0){
 					$timezone = substr($filename, 20);
diff --git a/src/pocketmine/utils/Utils.php b/src/pocketmine/utils/Utils.php
index 6312d56ce..0a37267c5 100644
--- a/src/pocketmine/utils/Utils.php
+++ b/src/pocketmine/utils/Utils.php
@@ -99,6 +99,14 @@ use const STR_PAD_RIGHT;
  * Big collection of functions
  */
 class Utils{
+	public const OS_WINDOWS = "win";
+	public const OS_IOS = "ios";
+	public const OS_MACOS = "mac";
+	public const OS_ANDROID = "android";
+	public const OS_LINUX = "linux";
+	public const OS_BSD = "bsd";
+	public const OS_UNKNOWN = "other";
+
 	/** @var string|null */
 	public static $os;
 	/** @var UUID|null */
@@ -186,7 +194,7 @@ class Utils{
 		$machine .= sys_get_temp_dir();
 		$machine .= $extra;
 		$os = Utils::getOS();
-		if($os === "win"){
+		if($os === Utils::OS_WINDOWS){
 			@exec("ipconfig /ALL", $mac);
 			$mac = implode("\n", $mac);
 			if(preg_match_all("#Physical Address[. ]{1,}: ([0-9A-F\\-]{17})#", $mac, $matches) > 0){
@@ -197,7 +205,7 @@ class Utils{
 				}
 				$machine .= implode(" ", $matches[1]); //Mac Addresses
 			}
-		}elseif($os === "linux"){
+		}elseif($os === Utils::OS_LINUX){
 			if(file_exists("/etc/machine-id")){
 				$machine .= file_get_contents("/etc/machine-id");
 			}else{
@@ -212,9 +220,9 @@ class Utils{
 					$machine .= implode(" ", $matches[1]); //Mac Addresses
 				}
 			}
-		}elseif($os === "android"){
+		}elseif($os === Utils::OS_ANDROID){
 			$machine .= @file_get_contents("/system/build.prop");
-		}elseif($os === "mac"){
+		}elseif($os === Utils::OS_MACOS){
 			$machine .= `system_profiler SPHardwareDataType | grep UUID`;
 		}
 		$data = $machine . PHP_MAXPATHLEN;
@@ -261,22 +269,22 @@ class Utils{
 			$uname = php_uname("s");
 			if(stripos($uname, "Darwin") !== false){
 				if(strpos(php_uname("m"), "iP") === 0){
-					self::$os = "ios";
+					self::$os = self::OS_IOS;
 				}else{
-					self::$os = "mac";
+					self::$os = self::OS_MACOS;
 				}
 			}elseif(stripos($uname, "Win") !== false or $uname === "Msys"){
-				self::$os = "win";
+				self::$os = self::OS_WINDOWS;
 			}elseif(stripos($uname, "Linux") !== false){
 				if(@file_exists("/system/build.prop")){
-					self::$os = "android";
+					self::$os = self::OS_ANDROID;
 				}else{
-					self::$os = "linux";
+					self::$os = self::OS_LINUX;
 				}
 			}elseif(stripos($uname, "BSD") !== false or $uname === "DragonFly"){
-				self::$os = "bsd";
+				self::$os = self::OS_BSD;
 			}else{
-				self::$os = "other";
+				self::$os = self::OS_UNKNOWN;
 			}
 		}
 
@@ -322,8 +330,8 @@ class Utils{
 		}
 
 		switch(Utils::getOS()){
-			case "linux":
-			case "android":
+			case Utils::OS_LINUX:
+			case Utils::OS_ANDROID:
 				if(($cpuinfo = @file('/proc/cpuinfo')) !== false){
 					foreach($cpuinfo as $l){
 						if(preg_match('/^processor[ \t]*:[ \t]*[0-9]+$/m', $l) > 0){
@@ -336,11 +344,11 @@ class Utils{
 					}
 				}
 				break;
-			case "bsd":
-			case "mac":
+			case Utils::OS_BSD:
+			case Utils::OS_MACOS:
 				$processors = (int) `sysctl -n hw.ncpu`;
 				break;
-			case "win":
+			case Utils::OS_WINDOWS:
 				$processors = (int) getenv("NUMBER_OF_PROCESSORS");
 				break;
 		}