diff --git a/contracts/sfc/SFC.sol b/contracts/sfc/SFC.sol
index f9c8a80..f1c04e6 100644
--- a/contracts/sfc/SFC.sol
+++ b/contracts/sfc/SFC.sol
@@ -1,4 +1,4 @@
-pragma solidity ^0.5.0;
+pragma solidity ^0.6.0;
 
 import "./GasPriceConstants.sol";
 import "../version/Version.sol";
@@ -134,8 +134,13 @@ contract SFC is SFCBase, Version {
         require(pubkeyHashToValidatorID[keccak256(pubkey)] == 0, "already used");
         require(validatorPubkeyChanges[validatorID] == 0 || validatorID == 64 || validatorID <= 12, "allowed only once");
 
+        address oldAddress = address(uint160(uint256(keccak256(getValidatorPubkey[validatorID][2:]))));
+        address newAddress = address(uint160(uint256(keccak256(pubkey[2:]))));
+
         validatorPubkeyChanges[validatorID]++;
         pubkeyHashToValidatorID[keccak256(pubkey)] = validatorID;
+        pubkeyAddressToValidatorID[oldAddress] = 0;
+        pubkeyAddressToValidatorID[newAddress] = validatorID;
         getValidatorPubkey[validatorID] = pubkey;
         _syncValidator(validatorID, true);
     }
diff --git a/contracts/sfc/SFCLib.sol b/contracts/sfc/SFCLib.sol
index 1a9a631..c327d35 100644
--- a/contracts/sfc/SFCLib.sol
+++ b/contracts/sfc/SFCLib.sol
@@ -1,4 +1,4 @@
-pragma solidity ^0.5.0;
+pragma solidity ^0.6.0;
 
 import "../common/Decimal.sol";
 import "./GasPriceConstants.sol";
@@ -63,7 +63,7 @@ contract SFCLib is SFCBase {
         _rawCreateValidator(auth, validatorID, pubkey, OK_STATUS, currentEpoch(), _now(), 0, 0);
     }
 
-    function _rawCreateValidator(address auth, uint256 validatorID, bytes memory pubkey, uint256 status, uint256 createdEpoch, uint256 createdTime, uint256 deactivatedEpoch, uint256 deactivatedTime) internal {
+    function _rawCreateValidator(address auth, uint256 validatorID, bytes calldata pubkey, uint256 status, uint256 createdEpoch, uint256 createdTime, uint256 deactivatedEpoch, uint256 deactivatedTime) internal {
         require(getValidatorID[auth] == 0, "validator already exists");
         getValidatorID[auth] = validatorID;
         getValidator[validatorID].status = status;
@@ -74,6 +74,7 @@ contract SFCLib is SFCBase {
         getValidator[validatorID].auth = auth;
         getValidatorPubkey[validatorID] = pubkey;
         pubkeyHashToValidatorID[keccak256(pubkey)] = validatorID;
+        pubkeyAddressToValidatorID[address(uint160(uint256(keccak256(pubkey[2:]))))] = validatorID;
 
         emit CreatedValidator(validatorID, auth, createdEpoch, createdTime);
         if (deactivatedEpoch != 0) {
diff --git a/contracts/sfc/SFCState.sol b/contracts/sfc/SFCState.sol
index cfa1d8a..6bdb785 100644
--- a/contracts/sfc/SFCState.sol
+++ b/contracts/sfc/SFCState.sol
@@ -125,4 +125,6 @@ contract SFCState is Initializable, Ownable {
     mapping(address => address) public getRedirectionRequest;
 
     mapping(address => address) public getRedirection;
+
+    mapping(address => uint256) internal pubkeyAddressToValidatorID;
 }