diff --git a/contracts/drafts/SignatureBouncer.sol b/contracts/drafts/SignatureBouncer.sol
index b3c9304f6..48d3cc493 100644
--- a/contracts/drafts/SignatureBouncer.sol
+++ b/contracts/drafts/SignatureBouncer.sol
@@ -87,7 +87,7 @@ contract SignatureBouncer is SignerRole {
      */
     function _isValidSignatureAndMethod(address account, bytes memory signature) internal view returns (bool) {
         bytes memory data = new bytes(_METHOD_ID_SIZE);
-        for (uint i = 0; i < data.length; i++) {
+        for (uint256 i = 0; i < data.length; i++) {
             data[i] = msg.data[i];
         }
         return _isValidDataHash(keccak256(abi.encodePacked(address(this), account, data)), signature);
@@ -102,7 +102,7 @@ contract SignatureBouncer is SignerRole {
         require(msg.data.length > _SIGNATURE_SIZE, "SignatureBouncer: data is too short");
 
         bytes memory data = new bytes(msg.data.length - _SIGNATURE_SIZE);
-        for (uint i = 0; i < data.length; i++) {
+        for (uint256 i = 0; i < data.length; i++) {
             data[i] = msg.data[i];
         }
 
diff --git a/contracts/mocks/ERC20PausableMock.sol b/contracts/mocks/ERC20PausableMock.sol
index 4c9cdb7f8..6b9584e02 100644
--- a/contracts/mocks/ERC20PausableMock.sol
+++ b/contracts/mocks/ERC20PausableMock.sol
@@ -5,7 +5,7 @@ import "./PauserRoleMock.sol";
 
 // mock class using ERC20Pausable
 contract ERC20PausableMock is ERC20Pausable, PauserRoleMock {
-    constructor (address initialAccount, uint initialBalance) public {
+    constructor (address initialAccount, uint256 initialBalance) public {
         _mint(initialAccount, initialBalance);
     }
 }
diff --git a/contracts/mocks/ERC777SenderRecipientMock.sol b/contracts/mocks/ERC777SenderRecipientMock.sol
index d329c221e..7ce0513f7 100644
--- a/contracts/mocks/ERC777SenderRecipientMock.sol
+++ b/contracts/mocks/ERC777SenderRecipientMock.sol
@@ -43,7 +43,7 @@ contract ERC777SenderRecipientMock is IERC777Sender, IERC777Recipient, ERC1820Im
         address operator,
         address from,
         address to,
-        uint amount,
+        uint256 amount,
         bytes calldata userData,
         bytes calldata operatorData
     ) external {
@@ -74,7 +74,7 @@ contract ERC777SenderRecipientMock is IERC777Sender, IERC777Recipient, ERC1820Im
         address operator,
         address from,
         address to,
-        uint amount,
+        uint256 amount,
         bytes calldata userData,
         bytes calldata operatorData
     ) external{
diff --git a/contracts/token/ERC20/ERC20Pausable.sol b/contracts/token/ERC20/ERC20Pausable.sol
index 3304cc033..92f456243 100644
--- a/contracts/token/ERC20/ERC20Pausable.sol
+++ b/contracts/token/ERC20/ERC20Pausable.sol
@@ -20,11 +20,11 @@ contract ERC20Pausable is ERC20, Pausable {
         return super.approve(spender, value);
     }
 
-    function increaseAllowance(address spender, uint addedValue) public whenNotPaused returns (bool) {
+    function increaseAllowance(address spender, uint256 addedValue) public whenNotPaused returns (bool) {
         return super.increaseAllowance(spender, addedValue);
     }
 
-    function decreaseAllowance(address spender, uint subtractedValue) public whenNotPaused returns (bool) {
+    function decreaseAllowance(address spender, uint256 subtractedValue) public whenNotPaused returns (bool) {
         return super.decreaseAllowance(spender, subtractedValue);
     }
 }
diff --git a/contracts/token/ERC777/IERC777Recipient.sol b/contracts/token/ERC777/IERC777Recipient.sol
index a46b30a9f..a67d8ca28 100644
--- a/contracts/token/ERC777/IERC777Recipient.sol
+++ b/contracts/token/ERC777/IERC777Recipient.sol
@@ -25,7 +25,7 @@ interface IERC777Recipient {
         address operator,
         address from,
         address to,
-        uint amount,
+        uint256 amount,
         bytes calldata userData,
         bytes calldata operatorData
     ) external;
diff --git a/contracts/token/ERC777/IERC777Sender.sol b/contracts/token/ERC777/IERC777Sender.sol
index 6a158c52d..0d8810eb5 100644
--- a/contracts/token/ERC777/IERC777Sender.sol
+++ b/contracts/token/ERC777/IERC777Sender.sol
@@ -25,7 +25,7 @@ interface IERC777Sender {
         address operator,
         address from,
         address to,
-        uint amount,
+        uint256 amount,
         bytes calldata userData,
         bytes calldata operatorData
     ) external;