diff --git a/changelog.d/15352.bugfix b/changelog.d/15352.bugfix
new file mode 100644
index 0000000000..36d6615cac
--- /dev/null
+++ b/changelog.d/15352.bugfix
@@ -0,0 +1 @@
+Fix missing app variable in mail subject for password resets. Contributed by Cyberes.
diff --git a/synapse/push/mailer.py b/synapse/push/mailer.py
index 93b255ced5..491a09b71d 100644
--- a/synapse/push/mailer.py
+++ b/synapse/push/mailer.py
@@ -149,7 +149,7 @@ class Mailer:
         await self.send_email(
             email_address,
             self.email_subjects.password_reset
-            % {"server_name": self.hs.config.server.server_name},
+            % {"server_name": self.hs.config.server.server_name, "app": self.app_name},
             template_vars,
         )