diff --git a/index.js b/index.js
index 0bb1a2f..045310b 100644
--- a/index.js
+++ b/index.js
@@ -92,7 +92,7 @@ function _cleanObject(obj) {
       cleanedArray.push(_cleanObject(elt));
     }
     return cleanedArray;
-  } else if (typeof obj === "object") {
+  } else if (typeof obj === "object" && obj !== null) {
 
     // Remove all of the array-style keys, and clean the values for the non array-style keys.
     const cleanedObject = {};