diff --git a/package.json b/package.json
index 37f1225..74d8d22 100644
--- a/package.json
+++ b/package.json
@@ -47,7 +47,7 @@
     "mocha": "^6.2.2"
   },
   "dependencies": {
-    "bn.js": "^4.4.0",
+    "bn.js": "^5.0.0",
     "brorand": "^1.0.1",
     "hash.js": "^1.0.0",
     "hmac-drbg": "^1.0.0",
diff --git a/test/ecdsa-test.js b/test/ecdsa-test.js
index 831ac19..183c2e8 100644
--- a/test/ecdsa-test.js
+++ b/test/ecdsa-test.js
@@ -61,7 +61,7 @@ describe('ECDSA', function() {
 
       it('should have `signature.s <= keys.ec.nh`', function() {
         // key.sign(msg, options)
-        var sign = keys.sign('hello', { canonical: true });
+        var sign = keys.sign(Buffer.from('hello'), { canonical: true });
         assert(sign.s.cmp(keys.ec.nh) <= 0);
       });