diff --git a/core/lib/Drupal/Core/Asset/AssetGroupSetHashTrait.php b/core/lib/Drupal/Core/Asset/AssetGroupSetHashTrait.php
index 1d805b4c32..660d1a12a9 100644
--- a/core/lib/Drupal/Core/Asset/AssetGroupSetHashTrait.php
+++ b/core/lib/Drupal/Core/Asset/AssetGroupSetHashTrait.php
@@ -36,6 +36,12 @@ protected function generateHash(array $group): string {
     ];
     foreach ($group['items'] as $key => $asset) {
       $normalized['asset_group']['items'][$key] = array_diff_key($asset, $group_keys, $omit_keys);
+      // If the version is set to -1, this means there is no version in the
+      // library definition. To ensure unique hashes when unversioned files
+      // change, replace the version with a hash of the file contents.
+      if ($asset['version'] === -1) {
+        $normalized['asset_group']['items'][$key]['version'] = hash('xxh64', file_get_contents($asset['data']));
+      }
     }
     // The asset array ensures that a valid hash can only be generated via the
     // same code base. Additionally use the hash salt to ensure that hashes are