diff --git a/src/mergerfs_webui.cpp b/src/mergerfs_webui.cpp
index 83d1c5ed..3331ad8f 100644
--- a/src/mergerfs_webui.cpp
+++ b/src/mergerfs_webui.cpp
@@ -209,8 +209,16 @@ void
 _get_kv(const httplib::Request &req_,
         httplib::Response      &res_)
 {
+  if(not req_.has_param("mount"))
+    {
+      res_.status = 400;
+      res_.set_content("mount param not set", "text/plain");
+      return;
+    }
+
   json j;
   std::string mount;
+  std::map<std::string,std::string> kvs;
 
   mount = req_.get_param_value("mount");