diff --git a/changelog.d/12231.doc b/changelog.d/12231.doc
new file mode 100644
index 000000000..16593d2b9
--- /dev/null
+++ b/changelog.d/12231.doc
@@ -0,0 +1 @@
+Fix the link to the module documentation in the legacy spam checker warning message.
diff --git a/synapse/config/spam_checker.py b/synapse/config/spam_checker.py
index a233a9ce0..4c52103b1 100644
--- a/synapse/config/spam_checker.py
+++ b/synapse/config/spam_checker.py
@@ -25,8 +25,8 @@ logger = logging.getLogger(__name__)
 LEGACY_SPAM_CHECKER_WARNING = """
 This server is using a spam checker module that is implementing the deprecated spam
 checker interface. Please check with the module's maintainer to see if a new version
-supporting Synapse's generic modules system is available.
-For more information, please see https://matrix-org.github.io/synapse/latest/modules.html
+supporting Synapse's generic modules system is available. For more information, please
+see https://matrix-org.github.io/synapse/latest/modules/index.html
 ---------------------------------------------------------------------------------------"""