diff --git a/package-lock.json b/package-lock.json
index ba65d21..253aecc 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -8632,7 +8632,7 @@
     },
     "os-tmpdir": {
       "version": "1.0.2",
-      "resolved": "http://registry.npmjs.org/os-tmpdir/-/os-tmpdir-1.0.2.tgz",
+      "resolved": "https://registry.npmjs.org/os-tmpdir/-/os-tmpdir-1.0.2.tgz",
       "integrity": "sha1-u+Z0BseaqFxc/sdm/lc0VV36EnQ="
     },
     "p-cancelable": {
@@ -9248,7 +9248,7 @@
     },
     "sprintf-js": {
       "version": "1.0.3",
-      "resolved": "http://registry.npmjs.org/sprintf-js/-/sprintf-js-1.0.3.tgz",
+      "resolved": "https://registry.npmjs.org/sprintf-js/-/sprintf-js-1.0.3.tgz",
       "integrity": "sha1-BOaSb2YolTVPPdAVIDYzuFcpfiw="
     },
     "sshpk": {
diff --git a/src/mimcsponge_gencontract.js b/src/mimcsponge_gencontract.js
index e9bac2c..eb7d27b 100644
--- a/src/mimcsponge_gencontract.js
+++ b/src/mimcsponge_gencontract.js
@@ -50,7 +50,11 @@ function createCode(seed, n) {
     C.addmod();         // e=t^5+xR xL k q (for next round: xL xR k q)
 
     for (let i=0; i<n-1; i++) {
-        ci = Web3Utils.keccak256(ci);
+        if (i < n-2) {
+          ci = Web3Utils.keccak256(ci);
+        } else {
+          ci = "0x00";
+        }
         C.swap(1);      // xR xL k q
         C.dup(3);       // q xR xL k q
         C.dup(3);       // k q xR xL k q
@@ -74,9 +78,9 @@ function createCode(seed, n) {
         C.addmod();     // e=t^5+xR xL k q (for next round: xL xR k q)
     }
 
-    C.push("0x00");
-    C.mstore();     // Save it to pos 0;
     C.push("0x20");
+    C.mstore();     // Save it to pos 0;
+    C.push("0x00");
     C.mstore();     // Save it to pos 1;
     C.push("0x40");
     C.push("0x00");