diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
new file mode 100644
index 000000000..86ebbc484
--- /dev/null
+++ b/.github/workflows/release.yml
@@ -0,0 +1,35 @@
+name: release
+
+on:
+  release:
+    types: [created]
+
+jobs:
+  flats:
+    runs-on: ubuntu-latest
+    steps:
+      - id: get_release
+        uses: bruceadams/get-release@v1.2.1
+        env:
+          GITHUB_TOKEN: ${{ github.token }}
+      - uses: actions/setup-node@v1
+        with:
+          node-version: 10
+      - uses: actions/checkout@v2
+      - uses: actions/cache@v2
+        id: npm-cache
+        with:
+          path: node_modules
+          key: ${{ runner.os }}-node_modules-${{ hashFiles('**/package-lock.json') }}
+      - run: npm install
+        if: ${{ !steps.npm-cache.outputs.cache-hit }}
+      - run: npm run flatten
+      - run: zip flats $(find flats -name '*.sol')
+      - uses: actions/upload-release-asset@v1.0.2
+        env:
+          GITHUB_TOKEN: ${{ github.token }}
+        with:
+          upload_url: ${{ steps.get_release.outputs.upload_url }}
+          asset_path: flats.zip
+          asset_name: tokenbridge-contracts-flattened-${{ steps.get_release.outputs.tag_name }}.zip
+          asset_content_type: application/zip
diff --git a/contracts/libraries/SafeERC20.sol b/contracts/libraries/SafeERC20.sol
new file mode 100644
index 000000000..58adf3983
--- /dev/null
+++ b/contracts/libraries/SafeERC20.sol
@@ -0,0 +1,49 @@
+pragma solidity 0.4.24;
+
+import "openzeppelin-solidity/contracts/math/SafeMath.sol";
+import "../interfaces/ERC677.sol";
+
+/**
+ * @title SafeERC20
+ * @dev Helper methods for safe token transfers.
+ * Functions perform additional checks to be sure that token transfer really happened.
+ */
+library SafeERC20 {
+    using SafeMath for uint256;
+
+    /**
+    * @dev Same as ERC20.transfer(address,uint256) but with extra consistency checks.
+    * @param _token address of the token contract
+    * @param _to address of the receiver
+    * @param _value amount of tokens to send
+    */
+    function safeTransfer(address _token, address _to, uint256 _value) internal {
+        LegacyERC20(_token).transfer(_to, _value);
+        assembly {
+            if returndatasize {
+                returndatacopy(0, 0, 32)
+                if iszero(mload(0)) {
+                    revert(0, 0)
+                }
+            }
+        }
+    }
+
+    /**
+    * @dev Same as ERC20.transferFrom(address,address,uint256) but with extra consistency checks.
+    * @param _token address of the token contract
+    * @param _from address of the sender
+    * @param _value amount of tokens to send
+    */
+    function safeTransferFrom(address _token, address _from, uint256 _value) internal {
+        LegacyERC20(_token).transferFrom(_from, address(this), _value);
+        assembly {
+            if returndatasize {
+                returndatacopy(0, 0, 32)
+                if iszero(mload(0)) {
+                    revert(0, 0)
+                }
+            }
+        }
+    }
+}
diff --git a/contracts/upgradeable_contracts/amb_erc20_to_native/BasicAMBErc20ToNative.sol b/contracts/upgradeable_contracts/amb_erc20_to_native/BasicAMBErc20ToNative.sol
index b256d30e1..2554c5293 100644
--- a/contracts/upgradeable_contracts/amb_erc20_to_native/BasicAMBErc20ToNative.sol
+++ b/contracts/upgradeable_contracts/amb_erc20_to_native/BasicAMBErc20ToNative.sol
@@ -51,7 +51,7 @@ contract BasicAMBErc20ToNative is Initializable, Upgradeable, Claimable, Version
     * @return patch value of the version
     */
     function getBridgeInterfacesVersion() external pure returns (uint64 major, uint64 minor, uint64 patch) {
-        return (1, 1, 0);
+        return (1, 1, 1);
     }
 
     /**
diff --git a/contracts/upgradeable_contracts/amb_erc20_to_native/ForeignAMBErc20ToNative.sol b/contracts/upgradeable_contracts/amb_erc20_to_native/ForeignAMBErc20ToNative.sol
index 152914f83..ee9290eec 100644
--- a/contracts/upgradeable_contracts/amb_erc20_to_native/ForeignAMBErc20ToNative.sol
+++ b/contracts/upgradeable_contracts/amb_erc20_to_native/ForeignAMBErc20ToNative.sol
@@ -3,6 +3,7 @@ pragma solidity 0.4.24;
 import "./BasicAMBErc20ToNative.sol";
 import "../BaseERC677Bridge.sol";
 import "../ReentrancyGuard.sol";
+import "../../libraries/SafeERC20.sol";
 
 /**
 * @title ForeignAMBErc20ToNative
@@ -10,6 +11,8 @@ import "../ReentrancyGuard.sol";
 * It is design to be used as implementation contract of EternalStorageProxy contract.
 */
 contract ForeignAMBErc20ToNative is BasicAMBErc20ToNative, ReentrancyGuard, BaseERC677Bridge {
+    using SafeERC20 for ERC677;
+
     bytes32 internal constant MEDIATOR_BALANCE = 0x3db340e280667ee926fa8c51e8f9fcf88a0ff221a66d84d63b4778127d97d139; // keccak256(abi.encodePacked("mediatorBalance"))
 
     /**
@@ -70,13 +73,12 @@ contract ForeignAMBErc20ToNative is BasicAMBErc20ToNative, ReentrancyGuard, Base
         // which will call passMessage.
         require(!lock());
         ERC677 token = _erc677token();
-        address to = address(this);
         require(withinLimit(_value));
         addTotalSpentPerDay(getCurrentDay(), _value);
         _setMediatorBalance(mediatorBalance().add(_value));
 
         setLock(true);
-        token.transferFrom(msg.sender, to, _value);
+        token.safeTransferFrom(msg.sender, _value);
         setLock(false);
         bridgeSpecificActionsOnTokenTransfer(token, msg.sender, _value, abi.encodePacked(_receiver));
     }
@@ -150,7 +152,7 @@ contract ForeignAMBErc20ToNative is BasicAMBErc20ToNative, ReentrancyGuard, Base
         bytes32 _messageId = messageId();
 
         _setMediatorBalance(mediatorBalance().sub(valueToTransfer));
-        _erc677token().transfer(_receiver, valueToTransfer);
+        _erc677token().safeTransfer(_receiver, valueToTransfer);
         emit TokensBridged(_receiver, valueToTransfer, _messageId);
     }
 
@@ -161,7 +163,7 @@ contract ForeignAMBErc20ToNative is BasicAMBErc20ToNative, ReentrancyGuard, Base
     */
     function executeActionOnFixedTokens(address _receiver, uint256 _value) internal {
         _setMediatorBalance(mediatorBalance().sub(_value));
-        _erc677token().transfer(_receiver, _value);
+        _erc677token().safeTransfer(_receiver, _value);
     }
 
     /**
diff --git a/contracts/upgradeable_contracts/amb_erc677_to_erc677/BasicAMBErc677ToErc677.sol b/contracts/upgradeable_contracts/amb_erc677_to_erc677/BasicAMBErc677ToErc677.sol
index 9b657fc7d..3ddc69905 100644
--- a/contracts/upgradeable_contracts/amb_erc677_to_erc677/BasicAMBErc677ToErc677.sol
+++ b/contracts/upgradeable_contracts/amb_erc677_to_erc677/BasicAMBErc677ToErc677.sol
@@ -62,6 +62,12 @@ contract BasicAMBErc677ToErc677 is
         return mediatorContractOnOtherSide();
     }
 
+    /**
+    * @dev Initiates the bridge operation that will lock the amount of tokens transferred and mint the tokens on
+    * the other network. The user should first call Approve method of the ERC677 token.
+    * @param _receiver address that will receive the minted tokens on the other network.
+    * @param _value amount of tokens to be transferred to the other network.
+    */
     function relayTokens(address _receiver, uint256 _value) external {
         // This lock is to prevent calling passMessage twice if a ERC677 token is used.
         // When transferFrom is called, after the transfer, the ERC677 token will call onTokenTransfer from this contract
@@ -90,7 +96,7 @@ contract BasicAMBErc677ToErc677 is
     }
 
     function getBridgeInterfacesVersion() external pure returns (uint64 major, uint64 minor, uint64 patch) {
-        return (1, 2, 0);
+        return (1, 2, 1);
     }
 
     function getBridgeMode() external pure returns (bytes4 _data) {
diff --git a/contracts/upgradeable_contracts/amb_erc677_to_erc677/ForeignAMBErc677ToErc677.sol b/contracts/upgradeable_contracts/amb_erc677_to_erc677/ForeignAMBErc677ToErc677.sol
index ac8e537cf..d65c29eb4 100644
--- a/contracts/upgradeable_contracts/amb_erc677_to_erc677/ForeignAMBErc677ToErc677.sol
+++ b/contracts/upgradeable_contracts/amb_erc677_to_erc677/ForeignAMBErc677ToErc677.sol
@@ -1,6 +1,7 @@
 pragma solidity 0.4.24;
 
 import "./BasicAMBErc677ToErc677.sol";
+import "../../libraries/SafeERC20.sol";
 
 /**
 * @title ForeignAMBErc677ToErc677
@@ -8,6 +9,8 @@ import "./BasicAMBErc677ToErc677.sol";
 * It is designed to be used as an implementation contract of EternalStorageProxy contract.
 */
 contract ForeignAMBErc677ToErc677 is BasicAMBErc677ToErc677 {
+    using SafeERC20 for ERC677;
+
     /**
      * @dev Executes action on the request to withdraw tokens relayed from the other network
      * @param _recipient address of tokens receiver
@@ -16,10 +19,31 @@ contract ForeignAMBErc677ToErc677 is BasicAMBErc677ToErc677 {
     function executeActionOnBridgedTokens(address _recipient, uint256 _value) internal {
         uint256 value = _unshiftValue(_value);
         bytes32 _messageId = messageId();
-        erc677token().transfer(_recipient, value);
+        erc677token().safeTransfer(_recipient, value);
         emit TokensBridged(_recipient, value, _messageId);
     }
 
+    /**
+    * @dev Initiates the bridge operation that will lock the amount of tokens transferred and mint the tokens on
+    * the other network. The user should first call Approve method of the ERC677 token.
+    * @param _receiver address that will receive the minted tokens on the other network.
+    * @param _value amount of tokens to be transferred to the other network.
+    */
+    function relayTokens(address _receiver, uint256 _value) external {
+        // This lock is to prevent calling passMessage twice if a ERC677 token is used.
+        // When transferFrom is called, after the transfer, the ERC677 token will call onTokenTransfer from this contract
+        // which will call passMessage.
+        require(!lock());
+        ERC677 token = erc677token();
+        require(withinLimit(_value));
+        addTotalSpentPerDay(getCurrentDay(), _value);
+
+        setLock(true);
+        token.safeTransferFrom(msg.sender, _value);
+        setLock(false);
+        bridgeSpecificActionsOnTokenTransfer(token, msg.sender, _value, abi.encodePacked(_receiver));
+    }
+
     /**
      * @dev Executes action on deposit of bridged tokens
      * @param _from address of tokens sender
@@ -38,6 +62,6 @@ contract ForeignAMBErc677ToErc677 is BasicAMBErc677ToErc677 {
     }
 
     function executeActionOnFixedTokens(address _recipient, uint256 _value) internal {
-        erc677token().transfer(_recipient, _value);
+        erc677token().safeTransfer(_recipient, _value);
     }
 }
diff --git a/contracts/upgradeable_contracts/multi_amb_erc20_to_erc677/BasicMultiAMBErc20ToErc677.sol b/contracts/upgradeable_contracts/multi_amb_erc20_to_erc677/BasicMultiAMBErc20ToErc677.sol
index 7783e3afd..7c73dbf8c 100644
--- a/contracts/upgradeable_contracts/multi_amb_erc20_to_erc677/BasicMultiAMBErc20ToErc677.sol
+++ b/contracts/upgradeable_contracts/multi_amb_erc20_to_erc677/BasicMultiAMBErc20ToErc677.sol
@@ -58,7 +58,7 @@ contract BasicMultiAMBErc20ToErc677 is
     * @return patch value of the version
     */
     function getBridgeInterfacesVersion() external pure returns (uint64 major, uint64 minor, uint64 patch) {
-        return (1, 1, 0);
+        return (1, 1, 1);
     }
 
     /**
diff --git a/contracts/upgradeable_contracts/multi_amb_erc20_to_erc677/ForeignMultiAMBErc20ToErc677.sol b/contracts/upgradeable_contracts/multi_amb_erc20_to_erc677/ForeignMultiAMBErc20ToErc677.sol
index 3e7830d21..71e37e89e 100644
--- a/contracts/upgradeable_contracts/multi_amb_erc20_to_erc677/ForeignMultiAMBErc20ToErc677.sol
+++ b/contracts/upgradeable_contracts/multi_amb_erc20_to_erc677/ForeignMultiAMBErc20ToErc677.sol
@@ -4,6 +4,7 @@ import "openzeppelin-solidity/contracts/token/ERC20/DetailedERC20.sol";
 import "./BasicMultiAMBErc20ToErc677.sol";
 import "./HomeMultiAMBErc20ToErc677.sol";
 import "../../libraries/TokenReader.sol";
+import "../../libraries/SafeERC20.sol";
 
 /**
  * @title ForeignMultiAMBErc20ToErc677
@@ -11,6 +12,9 @@ import "../../libraries/TokenReader.sol";
  * It is designed to be used as an implementation contract of EternalStorageProxy contract.
  */
 contract ForeignMultiAMBErc20ToErc677 is BasicMultiAMBErc20ToErc677 {
+    using SafeERC20 for address;
+    using SafeERC20 for ERC677;
+
     /**
     * @dev Stores the initial parameters of the mediator.
     * @param _bridgeContract the address of the AMB bridge contract.
@@ -53,7 +57,7 @@ contract ForeignMultiAMBErc20ToErc677 is BasicMultiAMBErc20ToErc677 {
      */
     function executeActionOnBridgedTokens(address _token, address _recipient, uint256 _value) internal {
         bytes32 _messageId = messageId();
-        LegacyERC20(_token).transfer(_recipient, _value);
+        _token.safeTransfer(_recipient, _value);
         _setMediatorBalance(_token, mediatorBalance(_token).sub(_value));
         emit TokensBridged(_token, _recipient, _value, _messageId);
     }
@@ -97,10 +101,9 @@ contract ForeignMultiAMBErc20ToErc677 is BasicMultiAMBErc20ToErc677 {
         // When transferFrom is called, after the transfer, the ERC677 token will call onTokenTransfer from this contract
         // which will call passMessage.
         require(!lock());
-        address to = address(this);
 
         setLock(true);
-        LegacyERC20(token).transferFrom(msg.sender, to, _value);
+        token.safeTransferFrom(msg.sender, _value);
         setLock(false);
         bridgeSpecificActionsOnTokenTransfer(token, msg.sender, _value, abi.encodePacked(_receiver));
     }
@@ -189,7 +192,7 @@ contract ForeignMultiAMBErc20ToErc677 is BasicMultiAMBErc20ToErc677 {
     */
     function executeActionOnFixedTokens(address _token, address _recipient, uint256 _value) internal {
         _setMediatorBalance(_token, mediatorBalance(_token).sub(_value));
-        LegacyERC20(_token).transfer(_recipient, _value);
+        _token.safeTransfer(_recipient, _value);
     }
 
     /**
diff --git a/package-lock.json b/package-lock.json
index 65f3f9c84..50d2644b0 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "tokenbridge-contracts",
-  "version": "5.4.0",
+  "version": "5.4.1",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/package.json b/package.json
index e7d5e34ee..3c0fd8520 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "tokenbridge-contracts",
-  "version": "5.4.0",
+  "version": "5.4.1",
   "description": "Bridge",
   "main": "index.js",
   "scripts": {