diff --git a/lib/protocol/base58.js b/lib/protocol/base58.js
index cf13573..8e7409e 100644
--- a/lib/protocol/base58.js
+++ b/lib/protocol/base58.js
@@ -1,3 +1,5 @@
+'use strict';
+
 var bs58 = require('bs58');
 
 var Base58 = function Base58(obj) {
diff --git a/lib/protocol/bufferreader.js b/lib/protocol/bufferreader.js
index bc2d6c6..c601f32 100644
--- a/lib/protocol/bufferreader.js
+++ b/lib/protocol/bufferreader.js
@@ -1,4 +1,6 @@
-var BN = require('./bn');
+'use strict';
+
+var BN = require('../crypto/bn');
 
 var BufferReader = function BufferReader(buf) {
   if (!(this instanceof BufferReader))
diff --git a/lib/protocol/bufferwriter.js b/lib/protocol/bufferwriter.js
index a61ff90..3258aaa 100644
--- a/lib/protocol/bufferwriter.js
+++ b/lib/protocol/bufferwriter.js
@@ -1,4 +1,4 @@
-var BN = require('./bn');
+'use strict';
 
 var BufferWriter = function BufferWriter(obj) {
   if (!(this instanceof BufferWriter))
diff --git a/lib/protocol/constants.js b/lib/protocol/constants.js
index 2c8b7e3..f358816 100644
--- a/lib/protocol/constants.js
+++ b/lib/protocol/constants.js
@@ -1,3 +1,5 @@
+'use strict';
+
 exports.mainnet = {
   pubkeyhash:   0x00,
   identity:     0x0f,
@@ -23,4 +25,4 @@ exports.testnet = {
 exports.ephemeral = {
   prefix:   0x0f,
   identity: 0x02
-}
+};
diff --git a/lib/protocol/varint.js b/lib/protocol/varint.js
index 5fc367a..0ba7f10 100644
--- a/lib/protocol/varint.js
+++ b/lib/protocol/varint.js
@@ -1,6 +1,8 @@
+'use strict';
+
 var BufferWriter = require('./bufferwriter');
 var BufferReader = require('./bufferreader');
-var BN = require('./bn');
+var BN = require('../crypto/bn');
 
 var Varint = function Varint(buf) {
   if (!(this instanceof Varint))