diff --git a/lib/__tests__/integration.spec.ts b/lib/__tests__/integration.spec.ts
index 0c1bae9..5cfb5a0 100644
--- a/lib/__tests__/integration.spec.ts
+++ b/lib/__tests__/integration.spec.ts
@@ -11,7 +11,7 @@ import {
 describe("EMV-TS", () => {
   it("should work", () => compareWithReferentialImpl("60606040523415600e"));
 
-  it.skip("should work with more complicated bytecode", () => {
+  it("should work with more complicated bytecode", () => {
     const bin = fs.readFileSync(join(__dirname, "./contracts/DumbContract.bin"), "utf-8");
     const abi = JSON.parse(fs.readFileSync(join(__dirname, "./contracts/DumbContract.abi"), "utf-8"));
     const contract = web3.eth.contract(abi).at("0x0");
diff --git a/lib/opcodes/__tests__/arithmetic.spec.ts b/lib/opcodes/__tests__/arithmetic.spec.ts
index 96700cf..d8dfdde 100644
--- a/lib/opcodes/__tests__/arithmetic.spec.ts
+++ b/lib/opcodes/__tests__/arithmetic.spec.ts
@@ -15,6 +15,15 @@ describe("arithmetic opcodes", () => {
       ));
   });
 
+  describe("SUB", () => {
+    it("SUB with overflow", () =>
+      compareWithReferentialImpl(
+        "7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff03",
+      ));
+
+    it.skip("SUB with minus sign");
+  });
+
   describe("DIV", () => {
     it("div with overflow", () =>
       compareWithReferentialImpl(
diff --git a/lib/opcodes/__tests__/memory.spec.ts b/lib/opcodes/__tests__/memory.spec.ts
index 3cb04d2..2090da8 100644
--- a/lib/opcodes/__tests__/memory.spec.ts
+++ b/lib/opcodes/__tests__/memory.spec.ts
@@ -7,4 +7,8 @@ describe("memory opcodes", () => {
     it("with more than 1 word size data", () =>
       compareWithReferentialImpl("7f4e616d655265670000000000000000f0000b0000000000000000000000000000606052"));
   });
+
+  describe("MLOAD", () => {
+    it("simple", () => compareWithReferentialImpl("6060600052600051"));
+  });
 });
diff --git a/lib/opcodes/arithmetic.ts b/lib/opcodes/arithmetic.ts
index e5c9a03..737c053 100644
--- a/lib/opcodes/arithmetic.ts
+++ b/lib/opcodes/arithmetic.ts
@@ -1,4 +1,4 @@
-import { Opcode, notImplementedError } from "./common";
+import { Opcode } from "./common";
 import { IMachineState } from "../VM";
 import { MAX_UINT_256 } from "../utils/bytes";
 import { BN } from "bn.js";
@@ -37,8 +37,14 @@ export class SubOpcode extends Opcode {
   static id = 0x03;
   static type = "SUB";
 
-  run(_state: IMachineState): void {
-    notImplementedError();
+  run(state: IMachineState): void {
+    const arg1 = state.stack.pop();
+    const arg2 = state.stack.pop();
+
+    const result = arg1.sub(arg2).mod(MAX_UINT_256);
+
+    state.pc += 1;
+    state.stack.push(result);
   }
 }
 
diff --git a/lib/opcodes/memory.ts b/lib/opcodes/memory.ts
index ed8eae0..134fe9d 100644
--- a/lib/opcodes/memory.ts
+++ b/lib/opcodes/memory.ts
@@ -1,6 +1,7 @@
 import { IMachineState, IEnvironment } from "../VM";
-import { Opcode, notImplementedError } from "./common";
+import { Opcode } from "./common";
 import { arrayCopy } from "../utils/arrays";
+import { BN } from "bn.js";
 
 /**
  * Stores full word in memory.
@@ -29,8 +30,14 @@ export class MLoadOpcode extends Opcode {
   static id = 0x51;
   static type = "MLOAD";
 
-  run(_state: IMachineState): void {
-    notImplementedError();
+  run(state: IMachineState): void {
+    const address = state.stack.pop().toNumber();
+    const valueRaw = state.memory.slice(address, address + 32);
+
+    const value = new BN(valueRaw, undefined, "be");
+
+    state.stack.push(value);
+    state.pc += 1;
   }
 }