diff --git a/core/jobs/playtime_entries.py b/core/jobs/playtime_entries.py
index b68378446b..06313e5bab 100644
--- a/core/jobs/playtime_entries.py
+++ b/core/jobs/playtime_entries.py
@@ -130,13 +130,14 @@ def do_run(self):
         email_subject = (
             f"Playtime Summaries {formatted_start_date} - {formatted_until_date}"
         )
-        attachment_name = (
-            f"playtime-summary-{formatted_start_date}-{formatted_until_date}"
-        )
+        attachment_extension = "csv"
+        attachment_name = f"playtime-summary-{formatted_start_date}-{formatted_until_date}.{attachment_extension}"
 
         # Write to a temporary file so we don't overflow the memory
         with TemporaryFile(
-            "w+", prefix=f"playtimereport{formatted_until_date}", suffix="csv"
+            "w+",
+            prefix=f"playtimereport{formatted_until_date}",
+            suffix=attachment_extension,
         ) as temp:
             # Write the data as a CSV
             writer = csv.writer(temp)
diff --git a/tests/core/jobs/test_playtime_entries.py b/tests/core/jobs/test_playtime_entries.py
index 0cef68e379..fabcee2e36 100644
--- a/tests/core/jobs/test_playtime_entries.py
+++ b/tests/core/jobs/test_playtime_entries.py
@@ -294,7 +294,7 @@ def test_do_run(self, db: DatabaseTransactionFixture):
             receivers=["reporting@test.email"],
             text="",
             attachments={
-                f"playtime-summary-{cutoff}-{until}": ""
+                f"playtime-summary-{cutoff}-{until}.csv": ""
             },  # Mock objects do not write data
         )