diff --git a/Documentation/gitprotocol-v2.txt b/Documentation/gitprotocol-v2.txt
index 837ea6171e..414bc625d5 100644
--- a/Documentation/gitprotocol-v2.txt
+++ b/Documentation/gitprotocol-v2.txt
@@ -362,7 +362,8 @@ included in the client's request:
 If the 'packfile-uris' feature is advertised, the following argument
 can be included in the client's request as well as the potential
 addition of the 'packfile-uris' section in the server's response as
-explained below.
+explained below. Note that at most one `packfile-uris` line can be sent
+to the server.
 
     packfile-uris <comma-separated-list-of-protocols>
 	Indicates to the server that the client is willing to receive
diff --git a/upload-pack.c b/upload-pack.c
index 8b47576ec7..2a5c52666e 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -1646,6 +1646,9 @@ static void process_args(struct packet_reader *request,
 		}
 
 		if (skip_prefix(arg, "packfile-uris ", &p)) {
+			if (data->uri_protocols.nr)
+				send_err_and_die(data,
+						 "multiple packfile-uris lines forbidden");
 			string_list_split(&data->uri_protocols, p, ',', -1);
 			continue;
 		}