diff --git a/contracts/lifecycle/Pausable.sol b/contracts/lifecycle/Pausable.sol
index 9ac044a7f..ad7d66089 100644
--- a/contracts/lifecycle/Pausable.sol
+++ b/contracts/lifecycle/Pausable.sol
@@ -13,15 +13,17 @@ contract Pausable is Ownable {
   bool public stopped;
 
   modifier stopInEmergency {
-    if (!stopped) {
-      _;
+    if (stopped) {
+      throw;
     }
+    _;
   }
   
   modifier onlyInEmergency {
-    if (stopped) {
-      _;
+    if (!stopped) {
+      throw;
     }
+    _;
   }
 
   // called by the owner on emergency, triggers stopped state
diff --git a/contracts/ownership/Shareable.sol b/contracts/ownership/Shareable.sol
index 62fbc2fee..0cbf7d37d 100644
--- a/contracts/ownership/Shareable.sol
+++ b/contracts/ownership/Shareable.sol
@@ -105,12 +105,13 @@ contract Shareable {
     return !(pending.ownersDone & ownerIndexBit == 0);
   }
 
+  // returns true when operation can be executed
   function confirmAndCheck(bytes32 _operation) internal returns (bool) {
     // determine what index the present sender is:
     uint index = ownerIndex[msg.sender];
     // make sure they're an owner
     if (index == 0) {
-      return;
+      throw;
     }
 
     var pending = pendings[_operation];
@@ -140,6 +141,7 @@ contract Shareable {
         pending.ownersDone |= ownerIndexBit;
       }
     }
+    return false;
   }
 
   function clearPending() internal {
diff --git a/contracts/token/ERC20.sol b/contracts/token/ERC20.sol
index e89c66caa..6efe7b5d4 100644
--- a/contracts/token/ERC20.sol
+++ b/contracts/token/ERC20.sol
@@ -1,18 +1,17 @@
 pragma solidity ^0.4.8;
 
 
+import './ERC20Basic.sol';
+
+
 /*
  * ERC20 interface
  * see https://github.com/ethereum/EIPs/issues/20
  */
-contract ERC20 {
-  uint public totalSupply;
-  function balanceOf(address who) constant returns (uint);
+contract ERC20 is ERC20Basic {
   function allowance(address owner, address spender) constant returns (uint);
 
-  function transfer(address to, uint value) returns (bool ok);
-  function transferFrom(address from, address to, uint value) returns (bool ok);
-  function approve(address spender, uint value) returns (bool ok);
-  event Transfer(address indexed from, address indexed to, uint value);
+  function transferFrom(address from, address to, uint value);
+  function approve(address spender, uint value);
   event Approval(address indexed owner, address indexed spender, uint value);
 }
diff --git a/contracts/token/StandardToken.sol b/contracts/token/StandardToken.sol
index dbf1bb393..9be7d0eeb 100644
--- a/contracts/token/StandardToken.sol
+++ b/contracts/token/StandardToken.sol
@@ -1,8 +1,8 @@
 pragma solidity ^0.4.8;
 
 
+import './BasicToken.sol';
 import './ERC20.sol';
-import '../SafeMath.sol';
 
 
 /**
@@ -12,19 +12,11 @@ import '../SafeMath.sol';
  * Based on code by FirstBlood:
  * https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
  */
-contract StandardToken is ERC20, SafeMath {
+contract StandardToken is BasicToken, ERC20 {
 
-  mapping(address => uint) balances;
   mapping (address => mapping (address => uint)) allowed;
 
-  function transfer(address _to, uint _value) returns (bool success) {
-    balances[msg.sender] = safeSub(balances[msg.sender], _value);
-    balances[_to] = safeAdd(balances[_to], _value);
-    Transfer(msg.sender, _to, _value);
-    return true;
-  }
-
-  function transferFrom(address _from, address _to, uint _value) returns (bool success) {
+  function transferFrom(address _from, address _to, uint _value) {
     var _allowance = allowed[_from][msg.sender];
 
     // Check is not needed because safeSub(_allowance, _value) will already throw if this condition is not met
@@ -34,17 +26,11 @@ contract StandardToken is ERC20, SafeMath {
     balances[_from] = safeSub(balances[_from], _value);
     allowed[_from][msg.sender] = safeSub(_allowance, _value);
     Transfer(_from, _to, _value);
-    return true;
-  }
-
-  function balanceOf(address _owner) constant returns (uint balance) {
-    return balances[_owner];
   }
 
-  function approve(address _spender, uint _value) returns (bool success) {
+  function approve(address _spender, uint _value) {
     allowed[msg.sender][_spender] = _value;
     Approval(msg.sender, _spender, _value);
-    return true;
   }
 
   function allowance(address _owner, address _spender) constant returns (uint remaining) {
diff --git a/test/Pausable.js b/test/Pausable.js
index 1625871b0..3ac39e55a 100644
--- a/test/Pausable.js
+++ b/test/Pausable.js
@@ -1,6 +1,7 @@
 'use strict';
 
-var PausableMock = artifacts.require('helpers/PausableMock.sol');
+const assertJump = require('./helpers/assertJump');
+const PausableMock = artifacts.require('helpers/PausableMock.sol');
 
 contract('Pausable', function(accounts) {
 
@@ -20,7 +21,11 @@ contract('Pausable', function(accounts) {
     let count0 = await Pausable.count();
     assert.equal(count0, 0);
 
-    await Pausable.normalProcess();
+    try {
+      await Pausable.normalProcess();
+    } catch(error) {
+      assertJump(error);
+    }
     let count1 = await Pausable.count();
     assert.equal(count1, 0);
   });
@@ -28,9 +33,13 @@ contract('Pausable', function(accounts) {
 
   it('can not take drastic measure in non-emergency', async function() {
     let Pausable = await PausableMock.new();
-    await Pausable.drasticMeasure();
-    let drasticMeasureTaken = await Pausable.drasticMeasureTaken();
+    try {
+      await Pausable.drasticMeasure();
+    } catch(error) {
+      assertJump(error);
+    }
 
+    const drasticMeasureTaken = await Pausable.drasticMeasureTaken();
     assert.isFalse(drasticMeasureTaken);
   });