diff --git a/src/stringify.js b/src/stringify.js
index 3e66728d..5d1c4c37 100644
--- a/src/stringify.js
+++ b/src/stringify.js
@@ -7,7 +7,7 @@ import validate from './validate.js';
 const byteToHex = [];
 
 for (let i = 0; i < 256; ++i) {
-  byteToHex.push((i + 0x100).toString(16).slice(1));
+  byteToHex.push((i + 0x100).toString(16).slice(1).toLowerCase());
 }
 
 export function unsafeStringify(arr, offset = 0) {
@@ -34,7 +34,7 @@ export function unsafeStringify(arr, offset = 0) {
     byteToHex[arr[offset + 13]] +
     byteToHex[arr[offset + 14]] +
     byteToHex[arr[offset + 15]]
-  ).toLowerCase();
+  );
 }
 
 function stringify(arr, offset = 0) {