diff --git a/Development/nmos/control_protocol_ws_api.cpp b/Development/nmos/control_protocol_ws_api.cpp
index 2fd5e1c67..c6f7d39a8 100644
--- a/Development/nmos/control_protocol_ws_api.cpp
+++ b/Development/nmos/control_protocol_ws_api.cpp
@@ -225,9 +225,6 @@ namespace nmos
             const auto& ws_ncp_path = connection_uri.path();
             slog::log<slog::severities::too_much_info>(gate, SLOG_FLF) << "Received websocket message: " << msg << " on connection: " << ws_ncp_path;
 
-            // extract the control protocol api version from the ws_ncp_path
-            const auto version = nmos::parse_api_version(web::uri::split_path(ws_ncp_path).back());
-
             auto websocket = websockets.right.find(connection_id);
             if (websockets.right.end() != websocket)
             {
@@ -241,6 +238,11 @@ namespace nmos
                     {
                         try
                         {
+                            // extract the control protocol api version from the ws_ncp_path
+                            if (web::uri::split_path(ws_ncp_path).empty()) { throw std::invalid_argument("empty URL"); }
+                            const auto version = nmos::parse_api_version(web::uri::split_path(ws_ncp_path).back());
+
+                            // convert message to JSON
                             const auto message = value::parse(utility::conversions::to_string_t(msg));
 
                             // validate the base-message