diff --git a/lib/base/webserver/impl/ShelfWebServer.dart b/lib/base/webserver/impl/ShelfWebServer.dart
index 958dec0..d8677a5 100644
--- a/lib/base/webserver/impl/ShelfWebServer.dart
+++ b/lib/base/webserver/impl/ShelfWebServer.dart
@@ -190,7 +190,13 @@ class ShelfWebServer implements WebServer {
     headers["Access-Control-Expose-Headers"] =
         "Content-Type,X-Span-ID,X-Trace-ID,token";
     headers['Access-Control-Allow-Methods'] = 'GET, POST, PUT, DELETE, OPTIONS';
-    headers["content-type"] = contentType;
+    var uct = headers["user-content-type"];
+    if (uct != null) {
+      headers.remove("user-content-type");
+      headers["content-type"] = uct;
+    } else {
+      headers["content-type"] = contentType;
+    }
 
     return response.change(headers: headers);
   }