diff --git a/changelog.d/11680.doc b/changelog.d/11680.doc
new file mode 100644
index 000000000000..09399ad9d0e6
--- /dev/null
+++ b/changelog.d/11680.doc
@@ -0,0 +1 @@
+Correct the documentation for `nginx` to use a case-sensitive url pattern. Fixes an error introduced in v1.21.0.
diff --git a/docs/reverse_proxy.md b/docs/reverse_proxy.md
index f3b3aea732c7..1a89da50fd97 100644
--- a/docs/reverse_proxy.md
+++ b/docs/reverse_proxy.md
@@ -63,7 +63,7 @@ server {
 
     server_name matrix.example.com;
 
-    location ~* ^(\/_matrix|\/_synapse\/client) {
+    location ~ ^(/_matrix|/_synapse/client) {
         # note: do not add a path (even a single /) after the port in `proxy_pass`,
         # otherwise nginx will canonicalise the URI and cause signature verification
         # errors.