diff --git a/ethereum/contracts/nft/NFTBridgeImplementation.sol b/ethereum/contracts/nft/NFTBridgeImplementation.sol
index 68b237a2..b00c3eb6 100644
--- a/ethereum/contracts/nft/NFTBridgeImplementation.sol
+++ b/ethereum/contracts/nft/NFTBridgeImplementation.sol
@@ -15,6 +15,10 @@ contract NFTBridgeImplementation is NFTBridge {
         return tokenImplementation();
     }
 
+    function initialize() initializer public virtual {
+        // this function needs to be exposed for an upgrade to pass
+    }
+
     modifier initializer() {
         address impl = ERC1967Upgrade._getImplementation();
 
diff --git a/ethereum/contracts/nft/mock/MockNFTBridgeImplementation.sol b/ethereum/contracts/nft/mock/MockNFTBridgeImplementation.sol
index ab457110..2787ef27 100644
--- a/ethereum/contracts/nft/mock/MockNFTBridgeImplementation.sol
+++ b/ethereum/contracts/nft/mock/MockNFTBridgeImplementation.sol
@@ -6,7 +6,7 @@ pragma solidity ^0.8.0;
 import "../NFTBridgeImplementation.sol";
 
 contract MockNFTBridgeImplementation is NFTBridgeImplementation {
-    function initialize() initializer public {
+    function initialize() initializer public override {
         // this function needs to be exposed for an upgrade to pass
     }