diff --git a/tests/unit/packaging/test_tasks.py b/tests/unit/packaging/test_tasks.py
index 54615096dede..09deec6761ac 100644
--- a/tests/unit/packaging/test_tasks.py
+++ b/tests/unit/packaging/test_tasks.py
@@ -930,7 +930,24 @@ def test_metadata_backfill(db_request, monkeypatch, metrics):
     ]
 
 
-def test_metadata_backfill_individual(db_request, monkeypatch, metrics):
+@pytest.mark.parametrize(
+    "path, requested_path",
+    [
+        # Regular path
+        (
+            "8a/6a/19...3b/pip-24.0-py3-none-any.whl",
+            "8a/6a/19...3b/pip-24.0-py3-none-any.whl",
+        ),
+        # Path with characters that need quoted
+        (
+            "da/5d/cc...0d/scalg-0.1.1#-py3-none-any.whl",
+            "da/5d/cc...0d/scalg-0.1.1%23-py3-none-any.whl",
+        ),
+    ],
+)
+def test_metadata_backfill_individual(
+    db_request, monkeypatch, metrics, path, requested_path
+):
     project = ProjectFactory()
     release1 = ReleaseFactory(project=project)
     release2 = ReleaseFactory(project=project)
@@ -942,7 +959,10 @@ def test_metadata_backfill_individual(db_request, monkeypatch, metrics):
     )
     FileFactory(release=release2, packagetype="sdist")
     backfillable_file = FileFactory(
-        release=release2, packagetype="bdist_wheel", metadata_file_sha256_digest=None
+        release=release2,
+        packagetype="bdist_wheel",
+        metadata_file_sha256_digest=None,
+        path=path,
     )
 
     metadata_contents = b"some\nmetadata\ncontents"
@@ -996,7 +1016,7 @@ def mock_open(filename, perms):
     assert dist_from_wheel_url.calls == [
         pretend.call(
             project.normalized_name,
-            f"https://files.example.com/packages/{backfillable_file.path}",
+            f"https://files.example.com/packages/{requested_path}",
             stub_session,
         )
     ]
diff --git a/warehouse/packaging/tasks.py b/warehouse/packaging/tasks.py
index 07c479808c14..16858f8f9fa5 100644
--- a/warehouse/packaging/tasks.py
+++ b/warehouse/packaging/tasks.py
@@ -15,6 +15,7 @@
 import logging
 import os
 import tempfile
+import urllib.parse
 
 from collections import namedtuple
 from itertools import product
@@ -95,7 +96,7 @@ def metadata_backfill_individual(request, file_id):
         return
 
     base_url = request.registry.settings.get("files.url")
-    file_url = base_url.format(path=file_.path)
+    file_url = urllib.parse.quote(base_url.format(path=file_.path), safe=":/")
     metrics = request.find_service(IMetricsService, context=None)
     cache_storage = request.find_service(IFileStorage, name="cache")
     archive_storage = request.find_service(IFileStorage, name="archive")