[L13] Not using the SafeMath library

packages/protocol/contracts/common/MetaTransactionWallet.sol

@@ -212,7 +212,7 @@ contract MetaTransactionWallet is
       "Input arrays must be same length"
     );
     uint256 dataPosition = 0;
-    for (uint256 i = 0; i < destinations.length; i++) {
+    for (uint256 i = 0; i < destinations.length; i.add(1)) {
       executeTransaction(destinations[i], values[i], sliceData(data, dataPosition, dataLengths[i]));
       dataPosition = dataPosition.add(dataLengths[i]);
     }

packages/protocol/contracts/common/UsingPrecompiles.sol

@@ -93,7 +93,7 @@ contract UsingPrecompiles {
     if (blockNumber % epochSize == 0) {
       return epochNumber;
     } else {
-      return epochNumber + 1;
+      return epochNumber.add(1);
     }
   }
 
@@ -243,7 +243,7 @@ contract UsingPrecompiles {
    * @return bytes32 data
    */
   function getBytes32FromBytes(bytes memory bs, uint256 start) internal pure returns (bytes32) {
-    require(bs.length >= start + 32, "slicing out of range");
+    require(bs.length >= start.add(32), "slicing out of range");
     bytes32 x;
     assembly {
       x := mload(add(bs, add(start, 32)))

packages/protocol/contracts/governance/DowntimeSlasher.sol

@@ -99,7 +99,7 @@ contract DowntimeSlasher is ICeloVersionedContract, SlasherUtil {
     );
 
     bytes32 bitmap;
-    for (uint256 blockNumber = startBlock; blockNumber <= endBlock; blockNumber++) {
+    for (uint256 blockNumber = startBlock; blockNumber <= endBlock; blockNumber.add(1)) {
       // The canonical signatures for block N are stored in the parent seal bitmap for block N+1.
       bitmap |= getParentSealBitmap(blockNumber.add(1));
     }

packages/protocol/contracts/governance/Election.sol

@@ -962,7 +962,7 @@ contract Election is
     FixidityLib.Fraction[] memory votesForNextMember = new FixidityLib.Fraction[](
       electionGroups.length
     );
-    for (uint256 i = 0; i < electionGroups.length; i++) {
+    for (uint256 i = 0; i < electionGroups.length; i.add(1)) {
       keys[i] = i;
       votesForNextMember[i] = FixidityLib.newFixed(
         votes.total.eligible.getValue(electionGroups[i])

packages/protocol/contracts/identity/Attestations.sol

@@ -629,7 +629,7 @@ contract Attestations is
     for (uint256 i = 0; i < identifiersToLookup.length; i = i.add(1)) {
       uint256 count = identifiers[identifiersToLookup[i]].accounts.length;
 
-      totalAddresses = totalAddresses + count;
+      totalAddresses = totalAddresses.add(count);
       matches[i] = count;
     }
 
@@ -651,7 +651,7 @@ contract Attestations is
     IAccounts accounts = getAccounts();
     uint256 issuersLength = numberValidatorsInCurrentSet();
     uint256[] memory issuers = new uint256[](issuersLength);
-    for (uint256 i = 0; i < issuersLength; i++) issuers[i] = i;
+    for (uint256 i = 0; i < issuersLength; i.add(1)) issuers[i] = i;
 
     require(unselectedRequest.attestationsRequested <= issuersLength, "not enough issuers");
 

packages/protocol/specs/harnesses/LockedGoldHarness.sol

@@ -1,10 +1,13 @@
 pragma solidity ^0.5.8;
 
 import "openzeppelin-solidity/contracts/token/ERC20/IERC20.sol";
+import "openzeppelin-solidity/contracts/math/SafeMath.sol";
 import "contracts/governance/LockedGold.sol";
 import "./GoldTokenHarness.sol";
 
 contract LockedGoldHarness is LockedGold {
+  using SafeMath for uint256;
+
   GoldTokenHarness goldToken;
 
   /* solhint-disable-next-line no-empty-blocks */
@@ -31,16 +34,16 @@ contract LockedGoldHarness is LockedGold {
     require(getAccounts().isAccount(account), "Unknown account");
     uint256 length = balances[account].pendingWithdrawals.length;
     uint256 total = 0;
-    for (uint256 i = 0; i < length; i++) {
+    for (uint256 i = 0; i < length; i.add(1)) {
       uint256 pendingValue = balances[account].pendingWithdrawals[i].value;
-      require(total + pendingValue >= total, "Pending value must be greater than 0");
-      total = total + pendingValue;
+      require(total.add(pendingValue) >= total, "Pending value must be greater than 0");
+      total = total.add(pendingValue);
     }
     return total;
   }
 
   function pendingWithdrawalsNotFull(address account) public view returns (bool) {
-    return balances[account].pendingWithdrawals.length + 2 >= 2; // we can add 2 more additional elements
+    return balances[account].pendingWithdrawals.length.add(2) >= 2; // we can add 2 more additional elements
   }
 
   function getPendingWithdrawalsLength(address account) external view returns (uint256) {

packages/protocol/specs/harnesses/RegistryHarness.sol

@@ -1,8 +1,11 @@
 pragma solidity ^0.5.8;
 
+import "openzeppelin-solidity/contracts/math/SafeMath.sol";
 import "./IRegistryExtended.sol";
 
 contract RegistryHarness is IRegistryExtended {
+  using SafeMath for uint256;
+
   bytes32 constant ATTESTATIONS_REGISTRY_ID = keccak256(abi.encodePacked("Attestations"));
   bytes32 constant LOCKED_GOLD_REGISTRY_ID = keccak256(abi.encodePacked("LockedGold"));
   bytes32 constant GAS_CURRENCY_WHITELIST_REGISTRY_ID = keccak256(
@@ -123,23 +126,23 @@ contract RegistryHarness is IRegistryExtended {
   }
 
   function transfer(address recipient, uint256 value) external returns (bool) {
-    goldToken_balanceOf[msg.sender] = getRandomUInt256() - value;
-    goldToken_balanceOf[recipient] = getRandomUInt256() + value;
+    goldToken_balanceOf[msg.sender] = getRandomUInt256().sub(value);
+    goldToken_balanceOf[recipient] = getRandomUInt256().add(value);
     return getRandomBool();
   }
 
   function getRandomBool() public returns (bool) {
-    randomIndex++;
+    randomIndex.add(1);
     return randomBoolMap[randomIndex];
   }
 
   function getRandomUInt256() public returns (uint256) {
-    randomIndex++;
+    randomIndex.add(1);
     return randomUInt256Map[randomIndex];
   }
 
   function getRandomAddress() public returns (address) {
-    randomIndex++;
+    randomIndex.add(1);
     return randomAddressMap[randomIndex];
   }