diff --git a/src/pocketmine/level/format/io/region/RegionGarbageMap.php b/src/pocketmine/level/format/io/region/RegionGarbageMap.php
index 6202007c8..d07652933 100644
--- a/src/pocketmine/level/format/io/region/RegionGarbageMap.php
+++ b/src/pocketmine/level/format/io/region/RegionGarbageMap.php
@@ -69,11 +69,14 @@ final class RegionGarbageMap{
 		/** @var RegionLocationTableEntry|null $prevEntry */
 		$prevEntry = null;
 		foreach($usedMap as $firstSector => $entry){
-			$expectedStart = ($prevEntry !== null ? $prevEntry->getLastSector() + 1 : RegionLoader::FIRST_SECTOR);
-			$actualStart = $entry->getFirstSector();
-			if($expectedStart < $actualStart){
+			$prevEndPlusOne = ($prevEntry !== null ? $prevEntry->getLastSector() + 1 : RegionLoader::FIRST_SECTOR);
+			$currentStart = $entry->getFirstSector();
+			if($prevEndPlusOne < $currentStart){
 				//found a gap in the table
-				$garbageMap[$expectedStart] = new RegionLocationTableEntry($expectedStart, $actualStart - $expectedStart, 0);
+				$garbageMap[$prevEndPlusOne] = new RegionLocationTableEntry($prevEndPlusOne, $currentStart - $prevEndPlusOne, 0);
+			}elseif($prevEndPlusOne > $currentStart){
+				//current entry starts inside the previous. This would be a bug since RegionLoader should prevent this
+				throw new AssumptionFailedError("Overlapping entries detected");
 			}
 			$prevEntry = $entry;
 		}