diff --git a/src/dfu.test.js b/src/dfu.test.js
index b7387285..95f95b84 100644
--- a/src/dfu.test.js
+++ b/src/dfu.test.js
@@ -215,7 +215,7 @@ describe('dfu', () => {
 
 	describe('doUpload', () => {
 		it ('handles startAddr NaN', async () => {
-			const startAddr = NaN;
+			const startAddr = 'abc';
 			const maxSize = 100;
 			const progress = null;
 			const logger = {