diff --git a/includes/resourceloader/ResourceLoaderFileModule.php b/includes/resourceloader/ResourceLoaderFileModule.php
index bed2d56e125..fe1f27aa4af 100644
--- a/includes/resourceloader/ResourceLoaderFileModule.php
+++ b/includes/resourceloader/ResourceLoaderFileModule.php
@@ -530,7 +530,7 @@ class ResourceLoaderFileModule extends ResourceLoaderModule {
 	 *
 	 * @see ResourceLoaderModule::getFileDependencies
 	 * @param ResourceLoaderContext $context
-	 * @return array
+	 * @return string
 	 */
 	private function getFileHashes( ResourceLoaderContext $context ) {
 		$files = [];
@@ -590,15 +590,11 @@ class ResourceLoaderFileModule extends ResourceLoaderModule {
 		// includes the entry point LESS file that we already have as a master file.
 		$files = array_unique( $files );
 
-		$hashes = [];
-		foreach ( $files as $file ) {
-			// Don't include array keys or any other form of file path here, only the hashes.
-			// Including file paths would needlessly cause global cache invalidation when files
-			// move on disk or if e.g. the MediaWiki directory name changes.
-			// Anything where order is significant is already detected by the definition summary.
-			$hashes[] = ResourceLoaderModule::safeFileHash( $file );
-		}
-		return $hashes;
+		// Don't return array keys or any other form of file path here, only the hashes.
+		// Including file paths would needlessly cause global cache invalidation when files
+		// move on disk or if e.g. the MediaWiki directory name changes.
+		// Anything where order is significant is already detected by the definition summary.
+		return FileContentsHasher::getFileContentsHash( $files );
 	}
 
 	/**
@@ -640,9 +636,9 @@ class ResourceLoaderFileModule extends ResourceLoaderModule {
 			// - The 'files' array, simplied to only which files exist (the keys of
 			//   this array), and something that represents their non-file content.
 			//   For packaged files that reflect files directly from disk, the
-			//   'getFileHashes' method tracks this already.
-			//   It is important that the keys of the 'files' array are preserved,
-			//   as they affect the module output.
+			//   'getFileHashes' method tracks their content already.
+			//   It is important that the keys of the $packageFiles['files'] array
+			//   are preserved, as they do affect the module output.
 			$packageFiles['files'] = array_map( function ( $fileInfo ) {
 				return $fileInfo['definitionSummary'] ?? ( $fileInfo['content'] ?? null );
 			}, $packageFiles['files'] );
diff --git a/includes/utils/FileContentsHasher.php b/includes/utils/FileContentsHasher.php
index e390f217c74..5343bcb54b5 100644
--- a/includes/utils/FileContentsHasher.php
+++ b/includes/utils/FileContentsHasher.php
@@ -48,12 +48,11 @@ class FileContentsHasher {
 	 * Get a hash of a file's contents, either by retrieving a previously-
 	 * computed hash from the cache, or by computing a hash from the file.
 	 *
-	 * @private
 	 * @param string $filePath Full path to the file.
 	 * @param string $algo Name of selected hashing algorithm.
 	 * @return string|bool Hash of file contents, or false if the file could not be read.
 	 */
-	public function getFileContentsHashInternal( $filePath, $algo = 'md4' ) {
+	private function getFileContentsHashInternal( $filePath, $algo = 'md4' ) {
 		$mtime = filemtime( $filePath );
 		if ( $mtime === false ) {
 			return false;
@@ -102,9 +101,10 @@ class FileContentsHasher {
 		}
 
 		sort( $filePaths );
-		$hashes = array_map( function ( $filePath ) use ( $instance, $algo ) {
-			return $instance->getFileContentsHashInternal( $filePath, $algo ) ?: '';
-		}, $filePaths );
+		$hashes = [];
+		foreach ( $filePaths as $filePath ) {
+			$hashes[] = $instance->getFileContentsHashInternal( $filePath, $algo ) ?: '';
+		}
 
 		Wikimedia\restoreWarnings();