diff --git a/src/data/bedrock/block/upgrade/BlockStateUpgradeSchemaUtils.php b/src/data/bedrock/block/upgrade/BlockStateUpgradeSchemaUtils.php
index 525c1c3bf..e6fe5c8dc 100644
--- a/src/data/bedrock/block/upgrade/BlockStateUpgradeSchemaUtils.php
+++ b/src/data/bedrock/block/upgrade/BlockStateUpgradeSchemaUtils.php
@@ -259,10 +259,11 @@ final class BlockStateUpgradeSchemaUtils{
 		$iterator = new \RegexIterator(
 			new \FilesystemIterator(
 				$path,
-				\FilesystemIterator::CURRENT_AS_PATHNAME | \FilesystemIterator::SKIP_DOTS | \FilesystemIterator::UNIX_PATHS
+				\FilesystemIterator::KEY_AS_FILENAME | \FilesystemIterator::SKIP_DOTS
 			),
-			'/\/(\d{4}).*\.json$/',
-			\RegexIterator::GET_MATCH
+			'/^(\d{4}).*\.json$/',
+			\RegexIterator::GET_MATCH,
+			\RegexIterator::USE_KEY
 		);
 
 		$result = [];
diff --git a/src/data/bedrock/item/upgrade/ItemIdMetaUpgradeSchemaUtils.php b/src/data/bedrock/item/upgrade/ItemIdMetaUpgradeSchemaUtils.php
index 9e95bf4a2..441ca02ee 100644
--- a/src/data/bedrock/item/upgrade/ItemIdMetaUpgradeSchemaUtils.php
+++ b/src/data/bedrock/item/upgrade/ItemIdMetaUpgradeSchemaUtils.php
@@ -42,10 +42,11 @@ final class ItemIdMetaUpgradeSchemaUtils{
 		$iterator = new \RegexIterator(
 			new \FilesystemIterator(
 				$path,
-				\FilesystemIterator::CURRENT_AS_PATHNAME | \FilesystemIterator::SKIP_DOTS | \FilesystemIterator::UNIX_PATHS
+				\FilesystemIterator::KEY_AS_FILENAME | \FilesystemIterator::SKIP_DOTS
 			),
-			'/\/(\d{4}).*\.json$/',
-			\RegexIterator::GET_MATCH
+			'/^(\d{4}).*\.json$/',
+			\RegexIterator::GET_MATCH,
+			\RegexIterator::USE_KEY
 		);
 
 		$result = [];