diff --git a/contracts/Delegation.sol b/contracts/Delegation.sol
index 5985398..b0d4fbe 100644
--- a/contracts/Delegation.sol
+++ b/contracts/Delegation.sol
@@ -47,7 +47,7 @@ abstract contract Delegation is Core {
     address[] memory from,
     uint256 proposalId,
     bool support
-  ) external {
+  ) external virtual {
     for (uint256 i = 0; i < from.length; i++) {
       require(delegatedTo[from[i]] == msg.sender, "Governance: not authorized");
       _castVote(from[i], proposalId, support);
diff --git a/contracts/Governance.sol b/contracts/Governance.sol
index bd7c5b0..68c615d 100644
--- a/contracts/Governance.sol
+++ b/contracts/Governance.sol
@@ -113,7 +113,7 @@ contract Governance is Initializable, Configuration, Delegation, EnsResolve {
     _transferTokens(msg.sender, amount);
   }
 
-  function unlock(uint256 amount) external {
+  function unlock(uint256 amount) external virtual {
     require(getBlockTimestamp() > canWithdrawAfter[msg.sender], "Governance: tokens are locked");
     lockedBalance[msg.sender] = lockedBalance[msg.sender].sub(amount, "Governance: insufficient balance");
     require(torn.transfer(msg.sender, amount), "TORN: transfer failed");
@@ -191,7 +191,7 @@ contract Governance is Initializable, Configuration, Delegation, EnsResolve {
     emit ProposalExecuted(proposalId);
   }
 
-  function castVote(uint256 proposalId, bool support) external {
+  function castVote(uint256 proposalId, bool support) external virtual {
     _castVote(msg.sender, proposalId, support);
   }
 
@@ -241,7 +241,7 @@ contract Governance is Initializable, Configuration, Delegation, EnsResolve {
     }
   }
 
-  function _transferTokens(address owner, uint256 amount) internal {
+  function _transferTokens(address owner, uint256 amount) internal virtual {
     require(torn.transferFrom(owner, address(this), amount), "TORN: transferFrom failed");
     lockedBalance[owner] = lockedBalance[owner].add(amount);
   }