diff --git a/cpp/JSI Utils/MGJSIMacros.h b/cpp/JSI Utils/MGJSIMacros.h
index 1a73c8b..8455a7a 100644
--- a/cpp/JSI Utils/MGJSIMacros.h	
+++ b/cpp/JSI Utils/MGJSIMacros.h	
@@ -19,6 +19,11 @@
         return jsi::Function::createFromHostFunction(runtime, propNameID, 0, func);    \
     })
 
+#define JSIF(capture)                                         \
+  capture(jsi::Runtime &runtime, const jsi::Value &thisValue, \
+          const jsi::Value *arguments, size_t count)          \
+      ->jsi::Value
+
 #define JSI_VALUE(name, body) JSI_VALUE_CAP(name, [=], body)
 
 #define JSI_VALUE_CAP(name, capture, body) std::make_pair(name, capture(jsi::Runtime &runtime) \
diff --git a/cpp/JSI Utils/MGSmartHostObject.cpp b/cpp/JSI Utils/MGSmartHostObject.cpp
index 05039cd..2df4a2f 100644
--- a/cpp/JSI Utils/MGSmartHostObject.cpp	
+++ b/cpp/JSI Utils/MGSmartHostObject.cpp	
@@ -21,6 +21,15 @@ namespace margelo
         return propertyNames;
     }
 
+    FieldDefinition buildPair(std::string name, jsi::HostFunctionType &&f) {
+      auto valueBuilder = [f, name](jsi::Runtime &runtime) {
+        const auto func = f;
+        auto propNameID = jsi::PropNameID::forAscii(runtime, name);
+        return jsi::Function::createFromHostFunction(runtime, propNameID, 0, func);
+      };
+      return std::make_pair(name, valueBuilder);
+    }
+
     // TODO(Szymon) maybe add memoization here
     jsi::Value MGSmartHostObject::get(jsi::Runtime &runtime,
                                       const jsi::PropNameID &propNameId)
@@ -37,4 +46,4 @@ namespace margelo
         return jsi::Value::undefined();
     }
 
-} // namespace margelo
\ No newline at end of file
+} // namespace margelo
diff --git a/cpp/JSI Utils/MGSmartHostObject.h b/cpp/JSI Utils/MGSmartHostObject.h
index ddbe150..4fe04f2 100644
--- a/cpp/JSI Utils/MGSmartHostObject.h	
+++ b/cpp/JSI Utils/MGSmartHostObject.h	
@@ -19,6 +19,8 @@ namespace margelo
 
     typedef std::pair<std::string, JSIValueBuilder> FieldDefinition;
 
+    FieldDefinition buildPair(std::string name, jsi::HostFunctionType &&f);
+
     class JSI_EXPORT MGSmartHostObject : public MGThreadAwareHostObject
     {
 
diff --git a/cpp/MGBigNumberHostObject.cpp b/cpp/MGBigNumberHostObject.cpp
index 48d2f64..9e8dd7e 100644
--- a/cpp/MGBigNumberHostObject.cpp
+++ b/cpp/MGBigNumberHostObject.cpp
@@ -1199,7 +1199,7 @@ namespace margelo
             return jsi::Value(runtime, BN_cmp(thiz->bign, other->bign) >= 0);
         }));
 
-        this->fields.push_back(HOST_LAMBDA("eq", {
+        this->fields.push_back(buildPair("eq", JSIF([this]) {
             std::shared_ptr<MGBigNumber> thiz = thisValue.getObject(runtime).getHostObject<MGBigNumber>(runtime);
             const jsi::Value &otherValue = arguments[0];
             if (!otherValue.isObject())
diff --git a/example/babel.config.js b/example/babel.config.js
index 26c852a..a8cb51f 100644
--- a/example/babel.config.js
+++ b/example/babel.config.js
@@ -12,6 +12,7 @@ module.exports = {
           [pak.name]: path.join(__dirname, '..', pak.source),
           bn_elliptic: path.join(__dirname, 'src', 'bn-elliptic', 'lib'),
           stream: 'stream-browserify',
+          "buffer":"@craftzdog/react-native-buffer"
         },
       },
     ],
diff --git a/example/ios/Podfile.lock b/example/ios/Podfile.lock
index a5b9ccf..ea29ef7 100644
--- a/example/ios/Podfile.lock
+++ b/example/ios/Podfile.lock
@@ -330,7 +330,7 @@ PODS:
   - React-jsinspector (0.71.6)
   - React-logger (0.71.6):
     - glog
-  - react-native-bignumber (0.1.9):
+  - react-native-bignumber (0.2.1):
     - OpenSSL-Universal (~> 1.1.180)
     - React
     - React-callinvoker
@@ -639,7 +639,7 @@ SPEC CHECKSUMS:
   React-jsiexecutor: 7894956638ff3e00819dd3f9f6f4a84da38f2409
   React-jsinspector: d5ce2ef3eb8fd30c28389d0bc577918c70821bd6
   React-logger: 9332c3e7b4ef007a0211c0a9868253aac3e1da82
-  react-native-bignumber: 055f50ffc80338573d199a560ee6f82a872c1c98
+  react-native-bignumber: 9850896db4534ea31e89dfd88182e7412eace199
   react-native-quick-base64: e657e9197e61b60a9dec49807843052b830da254
   react-native-safe-area-context: 39c2d8be3328df5d437ac1700f4f3a4f75716acc
   React-perflogger: 43392072a5b867a504e2b4857606f8fc5a403d7f
@@ -663,4 +663,4 @@ SPEC CHECKSUMS:
 
 PODFILE CHECKSUM: 3321d88aca920fdda50830e7db0b80420de18274
 
-COCOAPODS: 1.12.0
+COCOAPODS: 1.12.1
diff --git a/example/src/Testing/elliptic-tests/curves.ts b/example/src/Testing/elliptic-tests/curves.ts
index e1c3f52..9dccab6 100644
--- a/example/src/Testing/elliptic-tests/curves.ts
+++ b/example/src/Testing/elliptic-tests/curves.ts
@@ -1,7 +1,9 @@
-import { assert } from 'chai';
+import { assert, expect } from 'chai';
 import { describe, it } from '../MochaRNAdapter';
 import {BN} from 'react-native-bignumber';
 import elliptic from 'elliptic';
+import bn_elliptic from 'bn_elliptic';
+var SLOW_BN = require('bn.js');
 
 export function registerCurvedTests() {
   describe('Curve', function () {
@@ -20,6 +22,40 @@ export function registerCurvedTests() {
       assert(p.dbl().add(p.dbl()).eq(p.add(p).add(p).add(p)));
     });
 
+    it('issue #55 umod', function () {
+      const secp256k1 = new elliptic.ec('secp256k1');
+      const bn_secp256k1 = new bn_elliptic.ec('secp256k1');
+
+      const kI =
+        '9dc74cbfd383980fb4ae5d2680acddac9dac956dca65a28c80ac9c847c2374e4';
+      const n = secp256k1.curve.n;
+      const G = secp256k1.curve.g;
+      const Q = G.mul(kI);
+
+      const n_BN = bn_secp256k1.curve.n;
+      const G_BN = bn_secp256k1.curve.g;
+      const Q_BN = G_BN.mul(kI);
+
+      expect(`${Q.x.umod(n)}`).to.be.equal(`${Q_BN.x.umod(n_BN)}`);
+      
+      //console.log("FAST", Q.x.umod(n));
+      // output: e696d0036454d7b7890bd425947329f68d9c7c0e2de44958e5700a30ca98b02c
+      //console.log("SLOW", Q_BN.x.umod(n_BN));
+      // output: 54c4a33c6423d689378f160a7ff8b61330444abb58fb470f96ea16d99d4a2fed
+    })
+
+    it('issue #55 (simpler) umod', function () {
+      const SLOW_N = new SLOW_BN('fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141', 16);
+      const SLOW_Q = new SLOW_BN('54c4a33c6423d689378f160a7ff8b61330444abb58fb470f96ea16d99d4a2fed', 16);
+      const FAST_Q = new BN('54c4a33c6423d689378f160a7ff8b61330444abb58fb470f96ea16d99d4a2fed', 16);
+      const FAST_N = new BN('fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141', 16);
+      console.log('slow_n', SLOW_N);
+      console.log('slow_q', SLOW_Q);
+      console.log('res1', FAST_Q.umod(FAST_N));
+      console.log('res2', SLOW_Q.umod(SLOW_N));
+      expect(`${FAST_Q.umod(FAST_N)}`).to.be.equal(`${SLOW_Q.umod(SLOW_N)}`);
+    })
+
     it('should dbl points on edwards curve using proj coordinates', function () {
       var curve = new elliptic.curve.edwards({
         p: new BN(
diff --git a/src/BigNumber.ts b/src/BigNumber.ts
index a231732..8350879 100644
--- a/src/BigNumber.ts
+++ b/src/BigNumber.ts
@@ -356,7 +356,13 @@ export class BN {
   }
 
   umod(other: BN) {
-    return new BN(native.umod.call(this.internalBigNum, other.internalBigNum));
+    const res = new BN(
+      native.umod.call(this.internalBigNum, other.internalBigNum)
+    );
+    if (this.red) {
+      res.forceRed(this._mctx!);
+    }
+    return res;
   }
 
   imodn(other: number) {