diff --git a/index.js b/index.js
index 2645f5fa..55d112b1 100644
--- a/index.js
+++ b/index.js
@@ -164,6 +164,8 @@ exports.toBuffer = function (v) {
       v = exports.intToBuffer(v)
     } else if (v === null || v === undefined) {
       v = Buffer.allocUnsafe(0)
+    } else if (BN.isBN(v)) {
+      v = v.toArrayLike(Buffer)
     } else if (v.toArray) {
       // converts a BN to a Buffer
       v = Buffer.from(v.toArray())
diff --git a/package.json b/package.json
index 524e3f6e..c1fcea31 100644
--- a/package.json
+++ b/package.json
@@ -111,7 +111,7 @@
   },
   "homepage": "https://github.com/ethereumjs/ethereumjs-util",
   "dependencies": {
-    "bn.js": "^4.8.0",
+    "bn.js": "^4.11.0",
     "create-hash": "^1.1.2",
     "ethjs-util": "^0.1.3",
     "keccak": "^1.0.2",
diff --git a/test/index.js b/test/index.js
index f77abaac..966a6f36 100644
--- a/test/index.js
+++ b/test/index.js
@@ -436,8 +436,10 @@ describe('toBuffer', function () {
     assert.deepEqual(ethUtils.toBuffer(null), Buffer.allocUnsafe(0))
     // undefined
     assert.deepEqual(ethUtils.toBuffer(), Buffer.allocUnsafe(0))
-    // 'toArray'
+    // 'toBN'
     assert.deepEqual(ethUtils.toBuffer(new BN(1)), Buffer.from([1]))
+    // 'toArray'
+    assert.deepEqual(ethUtils.toBuffer({ toArray: function () { return [ 1 ] } }), Buffer.from([1]))
   })
   it('should fail', function () {
     assert.throws(function () {