diff --git a/config/hosts/matrix/nginx.nix b/config/hosts/matrix/nginx.nix
index 5a4f716..88c8e11 100644
--- a/config/hosts/matrix/nginx.nix
+++ b/config/hosts/matrix/nginx.nix
@@ -92,6 +92,8 @@
         # Then tell the realip_module to get the addreses from the proxy protocol
         # header.
         real_ip_header proxy_protocol;
+        # increase header buffer size because mjolnir sometimes uses very large URIs which nginx would normally block
+        large_client_header_buffers 4 16k;
       '';
     };