diff --git a/lib/core/Axios.js b/lib/core/Axios.js
index 8750f29dd6..31f8b531dc 100644
--- a/lib/core/Axios.js
+++ b/lib/core/Axios.js
@@ -61,7 +61,7 @@ class Axios {
       validator.assertOptions(paramsSerializer, {
         encode: validators.function,
         serialize: validators.function
-      }, false)
+      }, true);
     }
 
     // Set config.method