diff --git a/src/buildstream/downloadablefilesource.py b/src/buildstream/downloadablefilesource.py
index 3c7e05763..c9cb450b5 100644
--- a/src/buildstream/downloadablefilesource.py
+++ b/src/buildstream/downloadablefilesource.py
@@ -221,7 +221,7 @@ def _ensure_mirror(self, activity_name: str):
             # We do not use etag in case what we have in cache is
             # not matching ref in order to be able to recover from
             # corrupted download.
-            if self.ref and not self.is_cached():
+            if self.ref and self.is_cached():
                 # Do not re-download the file if the ETag matches.
                 etag = self._get_etag(self.ref)
             else: