diff --git a/lib/bcoin/hd.js b/lib/bcoin/hd.js
index fcc9f585..bf8975cc 100644
--- a/lib/bcoin/hd.js
+++ b/lib/bcoin/hd.js
@@ -324,7 +324,11 @@ HDPriv.prototype.derive = function(index, hard) {
 
   // XXX This causes a call stack overflow with bn.js@4.0.5 and elliptic@3.0.3
   // Example: new bn(0).mod(ec.curve.n)
-  var privateKey = leftPart.add(new bn(this.privateKey)).mod(ec.curve.n).toArray();
+  //var privateKey = leftPart.add(new bn(this.privateKey)).mod(ec.curve.n).toArray();
+
+  // Use this as a workaround:
+  var n = new bn('fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141', 'hex');
+  var privateKey = leftPart.add(new bn(this.privateKey)).mod(n).toArray();
 
   return new HDPriv({
     // version: this.version,