diff --git a/src/pocketmine/level/format/io/region/RegionLoader.php b/src/pocketmine/level/format/io/region/RegionLoader.php
index e86d3c56f..980dbbbd5 100644
--- a/src/pocketmine/level/format/io/region/RegionLoader.php
+++ b/src/pocketmine/level/format/io/region/RegionLoader.php
@@ -40,6 +40,7 @@ use function fseek;
 use function ftruncate;
 use function fwrite;
 use function is_resource;
+use function ksort;
 use function max;
 use function ord;
 use function pack;
@@ -314,6 +315,18 @@ class RegionLoader{
 			}
 			$usedOffsets[$offset] = $i;
 		}
+		ksort($usedOffsets, SORT_NUMERIC);
+		$prevLocationIndex = null;
+		foreach($usedOffsets as $startOffset => $locationTableIndex){
+			if($prevLocationIndex !== null){
+				if($this->locationTable[$locationTableIndex]->overlaps($this->locationTable[$prevLocationIndex])){
+					self::getChunkCoords($locationTableIndex, $chunkXX, $chunkZZ);
+					self::getChunkCoords($prevLocationIndex, $prevChunkXX, $prevChunkZZ);
+					throw new CorruptedRegionException("Overlapping chunks detected in region header (chunk1: x=$chunkXX,z=$chunkZZ, chunk2: x=$prevChunkXX,z=$prevChunkZZ)");
+				}
+			}
+			$prevLocationIndex = $locationTableIndex;
+		}
 	}
 
 	private function writeLocationTable() : void{
diff --git a/src/pocketmine/level/format/io/region/RegionLocationTableEntry.php b/src/pocketmine/level/format/io/region/RegionLocationTableEntry.php
index 167a9786a..3e97522f2 100644
--- a/src/pocketmine/level/format/io/region/RegionLocationTableEntry.php
+++ b/src/pocketmine/level/format/io/region/RegionLocationTableEntry.php
@@ -76,4 +76,17 @@ class RegionLocationTableEntry{
 	public function isNull() : bool{
 		return $this->firstSector === 0 or $this->sectorCount === 0;
 	}
+
+	public function overlaps(RegionLocationTableEntry $other) : bool{
+		$overlapCheck = static function(RegionLocationTableEntry $entry1, RegionLocationTableEntry $entry2) : bool{
+			$entry1Last = $entry1->getLastSector();
+			$entry2Last = $entry2->getLastSector();
+
+			return (
+				($entry2->firstSector >= $entry1->firstSector and $entry2->firstSector <= $entry1Last) or
+				($entry2Last >= $entry1->firstSector and $entry2Last <= $entry1Last)
+			);
+		};
+		return $overlapCheck($this, $other) or $overlapCheck($other, $this);
+	}
 }
diff --git a/tests/phpunit/level/format/io/region/RegionLocationTableEntryTest.php b/tests/phpunit/level/format/io/region/RegionLocationTableEntryTest.php
new file mode 100644
index 000000000..bf8550df4
--- /dev/null
+++ b/tests/phpunit/level/format/io/region/RegionLocationTableEntryTest.php
@@ -0,0 +1,52 @@
+<?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\level\format\io\region;
+
+use PHPUnit\Framework\TestCase;
+
+class RegionLocationTableEntryTest extends TestCase{
+
+	/**
+	 * @phpstan-return \Generator<int, array{RegionLocationTableEntry, RegionLocationTableEntry, bool}, void, void>
+	 */
+	public function overlapDataProvider() : \Generator{
+		yield [new RegionLocationTableEntry(2, 1, 0), new RegionLocationTableEntry(2, 1, 0), true];
+		yield [new RegionLocationTableEntry(2, 1, 0), new RegionLocationTableEntry(3, 1, 0), false];
+		yield [new RegionLocationTableEntry(2, 2, 0), new RegionLocationTableEntry(3, 2, 0), true];
+		yield [new RegionLocationTableEntry(2, 2, 0), new RegionLocationTableEntry(4, 2, 0), false];
+		yield [new RegionLocationTableEntry(2, 2, 0), new RegionLocationTableEntry(2, 1, 0), true];
+		yield [new RegionLocationTableEntry(2, 4, 0), new RegionLocationTableEntry(3, 1, 0), true];
+	}
+
+	/**
+	 * @dataProvider overlapDataProvider
+	 */
+	public function testOverlap(RegionLocationTableEntry $entry1, RegionLocationTableEntry $entry2, bool $overlaps) : void{
+		$stringify = function(RegionLocationTableEntry $entry) : string{
+			return sprintf("entry first=%d last=%d size=%d", $entry->getFirstSector(), $entry->getLastSector(), $entry->getSectorCount());
+		};
+		self::assertSame($overlaps, $entry1->overlaps($entry2), $stringify($entry1) . " expected to " . ($overlaps ? "overlap" : "not overlap") . " with " . $stringify($entry2));
+		self::assertSame($overlaps, $entry2->overlaps($entry1), $stringify($entry2) . " expected to " . ($overlaps ? "overlap" : "not overlap") . " with " . $stringify($entry1));
+	}
+}