diff --git a/src/pocketmine/utils/Config.php b/src/pocketmine/utils/Config.php
index ec3185631..d10c885ac 100644
--- a/src/pocketmine/utils/Config.php
+++ b/src/pocketmine/utils/Config.php
@@ -111,7 +111,7 @@ class Config{
 	 * @return string
 	 */
 	public static function fixYAMLIndexes(string $str) : string{
-		return preg_replace("#^([ ]*)([a-zA-Z_]{1}[ ]*)\\:$#m", "$1\"$2\":", $str);
+		return preg_replace("#^( *)(y|Y|yes|Yes|YES|n|N|no|No|NO|true|True|TRUE|false|False|FALSE|on|On|ON|off|Off|OFF)( *)\:#m", "$1\"$2\"$3:", $str);
 	}
 
 	/**
diff --git a/tests/phpunit/utils/ConfigTest.php b/tests/phpunit/utils/ConfigTest.php
new file mode 100644
index 000000000..7c48562ec
--- /dev/null
+++ b/tests/phpunit/utils/ConfigTest.php
@@ -0,0 +1,71 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+*/
+
+declare(strict_types=1);
+
+namespace pocketmine\utils;
+
+use PHPUnit\Framework\TestCase;
+
+class ConfigTest extends TestCase{
+
+	/**
+	 * @return \Generator
+	 */
+	public function fixYamlIndexesProvider() : \Generator{
+		yield ["x: 1\ny: 2\nz: 3\n", [
+			"x" => 1,
+			"y" => 2,
+			"z" => 3
+		]];
+		yield [" x : 1\n y : 2\n z : 3\n", [
+			"x" => 1,
+			"y" => 2,
+			"z" => 3
+		]];
+		yield ["parent:\n x: 1\n y: 2\n z: 3\n", [
+			"parent" => [
+				"x" => 1,
+				"y" => 2,
+				"z" => 3
+			]
+		]];
+		yield ["yes: notransform", [
+			"yes" => "notransform"
+		]];
+		yield ["on: 1\nyes: true", [ //this would previously have resulted in a key collision
+			"on" => 1,
+			"yes" => true
+		]];
+	}
+
+	/**
+	 * @dataProvider fixYamlIndexesProvider
+	 *
+	 * @param string $test
+	 * @param array  $expected
+	 */
+	public function testFixYamlIndexes(string $test, array $expected) : void{
+		$fixed = Config::fixYAMLIndexes($test);
+		$decoded = yaml_parse($fixed);
+		self::assertEquals($expected, $decoded);
+	}
+}