diff --git a/src/js/sjcl-custom/sjcl-validecc.js b/src/js/sjcl-custom/sjcl-validecc.js
index 99ecde39..7d24fd3b 100644
--- a/src/js/sjcl-custom/sjcl-validecc.js
+++ b/src/js/sjcl-custom/sjcl-validecc.js
@@ -17,7 +17,7 @@ sjcl.ecc.ecdsa.publicKey.prototype = {
         l = R.bitLength(),
         r = sjcl.bn.fromBits(w.bitSlice(rs,0,l)),
         s = sjcl.bn.fromBits(w.bitSlice(rs,l,2*l)),
-        sInv = s.modInverse(R),
+        sInv = s.inverseMod(R),
         hG = sjcl.bn.fromBits(hash).mul(sInv).mod(R),
         hA = r.mul(sInv).mod(R),
         r2 = this._curve.G.mult2(hG, hA, this._point).x;