diff --git a/src/mergerfs_webui.cpp b/src/mergerfs_webui.cpp
index 0ac72dbf..3b4060b3 100644
--- a/src/mergerfs_webui.cpp
+++ b/src/mergerfs_webui.cpp
@@ -348,6 +348,11 @@ _post_kvs_key(const httplib::Request &req_,
       std::string val;
 
       fmt::print(req_.body);
+
+      res_.set_content("",
+                       "application/json");
+
+
       j = json::parse(req_.body);
       key = req_.path_params.at("key");
       val = j;