diff --git a/changelog.d/13538.doc b/changelog.d/13538.doc
new file mode 100644
index 0000000000000000000000000000000000000000..9215aeac5a02df7cf81c5236d8109395c96b027e
--- /dev/null
+++ b/changelog.d/13538.doc
@@ -0,0 +1 @@
+Fix the doc and some warnings that were referring to the nonexistent `custom_templates_directory` setting (instead of `custom_template_directory`).
\ No newline at end of file
diff --git a/docs/templates.md b/docs/templates.md
index f87692a4538d04bb25b5e4e6d6c9d7f9f7025968..453ac90dd8918e8684d35bd4f2204f2eda8edb05 100644
--- a/docs/templates.md
+++ b/docs/templates.md
@@ -9,7 +9,7 @@ in, allowing them to specify custom templates:
 
 ```yaml
 templates:
-  custom_templates_directory: /path/to/custom/templates/
+  custom_template_directory: /path/to/custom/templates/
 ```
 
 If this setting is not set, or the files named below are not found within the directory,
diff --git a/synapse/config/account_validity.py b/synapse/config/account_validity.py
index d1335e77cdb388e8e737240438aae1dbf37d8b43..b3972ede96d3fe1cc5b82495a6a7eee2ea89288f 100644
--- a/synapse/config/account_validity.py
+++ b/synapse/config/account_validity.py
@@ -23,7 +23,7 @@ LEGACY_TEMPLATE_DIR_WARNING = """
 This server's configuration file is using the deprecated 'template_dir' setting in the
 'account_validity' section. Support for this setting has been deprecated and will be
 removed in a future version of Synapse. Server admins should instead use the new
-'custom_templates_directory' setting documented here:
+'custom_template_directory' setting documented here:
 https://matrix-org.github.io/synapse/latest/templates.html
 ---------------------------------------------------------------------------------------"""
 
diff --git a/synapse/config/emailconfig.py b/synapse/config/emailconfig.py
index 7765c5b4541707f951bb5a978b030ddb6e9d8e46..66a6dbf1fe943525be6f53b034f43eb0d07168b6 100644
--- a/synapse/config/emailconfig.py
+++ b/synapse/config/emailconfig.py
@@ -53,7 +53,7 @@ LEGACY_TEMPLATE_DIR_WARNING = """
 This server's configuration file is using the deprecated 'template_dir' setting in the
 'email' section. Support for this setting has been deprecated and will be removed in a
 future version of Synapse. Server admins should instead use the new
-'custom_templates_directory' setting documented here:
+'custom_template_directory' setting documented here:
 https://matrix-org.github.io/synapse/latest/templates.html
 ---------------------------------------------------------------------------------------"""
 
diff --git a/synapse/config/sso.py b/synapse/config/sso.py
index 2178cbf983770e516bbae64cef11c35dfc9e322d..a452cc3a496816b3e9ad4abe26a8ffe367f88506 100644
--- a/synapse/config/sso.py
+++ b/synapse/config/sso.py
@@ -26,7 +26,7 @@ LEGACY_TEMPLATE_DIR_WARNING = """
 This server's configuration file is using the deprecated 'template_dir' setting in the
 'sso' section. Support for this setting has been deprecated and will be removed in a
 future version of Synapse. Server admins should instead use the new
-'custom_templates_directory' setting documented here:
+'custom_template_directory' setting documented here:
 https://matrix-org.github.io/synapse/latest/templates.html
 ---------------------------------------------------------------------------------------"""