diff --git a/changelog.d/16404.bugfix b/changelog.d/16404.bugfix
new file mode 100644
index 000000000000..3fd5028b33f9
--- /dev/null
+++ b/changelog.d/16404.bugfix
@@ -0,0 +1 @@
+Fixes possbile `AttributeError` when `_matrix/client/v3/account/whoami` is called over a unix socket. Contributed by @Sir-Photch.
diff --git a/synapse/api/auth/internal.py b/synapse/api/auth/internal.py
index a75f6f2cc44e..36ee9c8b8fc8 100644
--- a/synapse/api/auth/internal.py
+++ b/synapse/api/auth/internal.py
@@ -115,7 +115,7 @@ async def _wrapped_get_user_by_req(
         Once get_user_by_req has set up the opentracing span, this does the actual work.
         """
         try:
-            ip_addr = request.getClientAddress().host
+            ip_addr = request.get_client_ip_if_available()
             user_agent = get_request_user_agent(request)
 
             access_token = self.get_access_token_from_request(request)