diff --git a/lib/browser/Key.js b/lib/browser/Key.js
index 088c64b..c931f1b 100644
--- a/lib/browser/Key.js
+++ b/lib/browser/Key.js
@@ -160,6 +160,12 @@ Key.sign = function(hash, priv, k) {
     var Q = Point.multiply(G, k);
     var r = Q.x.mod(n);
     var s = k.invm(n).mul(e.add(d.mul(r))).mod(n);
+    //enforce low s
+    //see BIP 62, "low S values in signatures"
+    var n_half = bignum.fromBuffer(new Buffer("7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0", 'hex'), {size: 32});
+    if (s.cmp(n_half) > 0) {
+      s = new bignum(n).sub(s);
+    }
   } while (r.cmp(new bignum(0)) <= 0 || s.cmp(new bignum(0)) <= 0);
 
   return {r: r, s: s};