diff --git a/lib/cartodb/cartodb_windshaft.js b/lib/cartodb/cartodb_windshaft.js
index cc3151d0..d18cf4e3 100644
--- a/lib/cartodb/cartodb_windshaft.js
+++ b/lib/cartodb/cartodb_windshaft.js
@@ -46,9 +46,13 @@ var CartodbWindshaft = function(serverOptions) {
     // See http://github.com/CartoDB/Windshaft-cartodb/issues/107
     var ws_sendError = ws.sendError;
     ws.sendError = function(res) {
-      delete res._headers['cache-control'];
-      delete res._headers['last-modified'];
-      delete res._headers['x-cache-channel'];
+      if ( res._headers ) {
+        delete res._headers['cache-control'];
+        delete res._headers['last-modified'];
+        delete res._headers['x-cache-channel'];
+      } else {
+        console.log("WARNING: response has no _headers: "); console.dir(res);
+      }
       ws_sendError.apply(this, arguments);
     };