diff --git a/src/create-object.js b/src/create-object.js
index 4566610..891ebe7 100644
--- a/src/create-object.js
+++ b/src/create-object.js
@@ -22,12 +22,12 @@ module.exports = function createObject(options) {
 		set: function setProperties(properties) {
 			Object.assign(this, properties);
 
-			if (properties.some(property => this.sizeBustingProperties.includes(property))) {
+			if (Object.keys(properties).some(property => this.sizeBustingProperties.includes(property))) {
 				this.emit("bustedSize");
 				this.recalculateSize();
 			}
 
-			if (properties.some(property => this.cacheBustingProperties.includes(property))) {
+			if (Object.keys(properties).some(property => this.cacheBustingProperties.includes(property))) {
 				this.emit("bustedCache");
 				this.isCached = false;
 			}