diff --git a/package-lock.json b/package-lock.json
index 6a0423a..f4add0b 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -632,12 +632,12 @@
       }
     },
     "circom": {
-      "version": "0.5.9",
-      "resolved": "https://registry.npmjs.org/circom/-/circom-0.5.9.tgz",
-      "integrity": "sha512-SCJoY2FoVpFsRlRcmRgLP5ko0jSxREAmQh7CM6gQ6V9KI5wXm8vR+5phj6wek/p0TnO5s3wR88JPMfjAm8P2Mw==",
+      "version": "0.5.10",
+      "resolved": "https://registry.npmjs.org/circom/-/circom-0.5.10.tgz",
+      "integrity": "sha512-50cVHDG7EbkuS6Ht3SDKBDeR/2M+/XSUxfpJMBL1TmFO2B/ucwUIwBNS00bpdtkT080dqwOVtuiYTLQ27prImw==",
       "requires": {
         "chai": "^4.2.0",
-        "circom_runtime": "0.0.5",
+        "circom_runtime": "0.0.6",
         "fastfile": "0.0.1",
         "ffiasm": "0.0.2",
         "ffjavascript": "0.1.0",
@@ -649,9 +649,9 @@
       }
     },
     "circom_runtime": {
-      "version": "0.0.5",
-      "resolved": "https://registry.npmjs.org/circom_runtime/-/circom_runtime-0.0.5.tgz",
-      "integrity": "sha512-WEZHnRO1AJIDI2w1yX6rq4G1/MMKnExT3qirjBQR7x43i9Ww3E/wusBHTbXWLb8aYyxsBU07LGy0YXPywPGYvA==",
+      "version": "0.0.6",
+      "resolved": "https://registry.npmjs.org/circom_runtime/-/circom_runtime-0.0.6.tgz",
+      "integrity": "sha512-o0T5MuWzxnxinWG3+CygS/kZouoP+z5ZrufUwqKJy3gsVFJhkbqMpfKmcBGjhExB3uatA7cKyOiRAOLOz5+t5w==",
       "requires": {
         "ffjavascript": "0.1.0",
         "fnv-plus": "^1.3.1"
diff --git a/package.json b/package.json
index 959ba8e..e1dc183 100644
--- a/package.json
+++ b/package.json
@@ -26,7 +26,7 @@
   "dependencies": {
     "blake-hash": "^1.1.0",
     "blake2b": "^2.1.3",
-    "circom": "0.5.9",
+    "circom": "0.5.10",
     "ffjavascript": "0.1.0",
     "web3": "^1.2.6"
   },
diff --git a/src/smt_memdb.js b/src/smt_memdb.js
index d752fa3..ccb85c6 100644
--- a/src/smt_memdb.js
+++ b/src/smt_memdb.js
@@ -1,6 +1,7 @@
 
 const F = require("./poseidon.js").F;
 const Scalar = require("ffjavascript").Scalar;
+const utils = require("ffjavascript").utils;
 
 class SMTMemDb {
     constructor() {
@@ -14,7 +15,7 @@ class SMTMemDb {
 
     _key2str(k) {
         // const keyS = bigInt(key).leInt2Buff(32).toString("hex");
-        const keyS = Scalar.e(k);
+        const keyS = k.toString();
         return keyS;
     }