diff --git a/contracts/facets/MeTokenRegistryFacet.sol b/contracts/facets/MeTokenRegistryFacet.sol
index ecd56377..6ef9432c 100644
--- a/contracts/facets/MeTokenRegistryFacet.sol
+++ b/contracts/facets/MeTokenRegistryFacet.sol
@@ -152,8 +152,6 @@ contract MeTokenRegistryFacet is
         MeTokenInfo storage meTokenInfo = s.meTokens[meToken];
         require(LibMeta.msgSender() == meTokenInfo.owner, "!owner");
         require(meTokenInfo.targetHubId != 0, "!resubscribing");
-        // TODO: validiate !IMigration(meTokenInfo.migration).migrationStarted(meToken)
-        // and do this interface for sameAssetMigration
         require(
             IMigration(meTokenInfo.migration).canCancelResubscribe(meToken),
             "cannot cancel resubscribe"
diff --git a/contracts/interfaces/IVault.sol b/contracts/interfaces/IVault.sol
index 29622479..15a271c6 100644
--- a/contracts/interfaces/IVault.sol
+++ b/contracts/interfaces/IVault.sol
@@ -91,5 +91,5 @@ interface IVault {
     ///           when a vault is registered to a new hub
     /// @param encodedArgs  Additional encoded arguments
     /// @return             True if encoded args are valid, else false
-    function isValid(bytes memory encodedArgs) external returns (bool);
+    function isValid(bytes memory encodedArgs) external pure returns (bool);
 }
diff --git a/contracts/migrations/SameAssetTransferMigration.sol b/contracts/migrations/SameAssetTransferMigration.sol
index e87ff9cd..c9cda689 100644
--- a/contracts/migrations/SameAssetTransferMigration.sol
+++ b/contracts/migrations/SameAssetTransferMigration.sol
@@ -115,13 +115,6 @@ contract SameAssetTransferMigration is ReentrancyGuard, Vault, IMigration {
         usts = _sameAssetMigration[meToken];
     }
 
-    /// @inheritdoc Vault
-    function isValid(
-        bytes memory /* encodedArgs */
-    ) external view override returns (bool) {
-        return true;
-    }
-
     /// @inheritdoc IMigration
     function migrationStarted(address meToken)
         external
@@ -140,4 +133,11 @@ contract SameAssetTransferMigration is ReentrancyGuard, Vault, IMigration {
     {
         return !_sameAssetMigration[meToken].started;
     }
+
+    /// @inheritdoc Vault
+    function isValid(
+        bytes memory /* encodedArgs */
+    ) external pure override returns (bool) {
+        return true;
+    }
 }
diff --git a/contracts/migrations/UniswapSingleTransferMigration.sol b/contracts/migrations/UniswapSingleTransferMigration.sol
index fcd09773..e0d46b86 100644
--- a/contracts/migrations/UniswapSingleTransferMigration.sol
+++ b/contracts/migrations/UniswapSingleTransferMigration.sol
@@ -139,21 +139,6 @@ contract UniswapSingleTransferMigration is ReentrancyGuard, Vault, IMigration {
         usts = _uniswapSingleTransfers[meToken];
     }
 
-    /// @inheritdoc Vault
-    function isValid(bytes memory encodedArgs)
-        external
-        view
-        override
-        returns (bool)
-    {
-        // encodedArgs empty
-        if (encodedArgs.length == 0) return false;
-        uint24 fee = abi.decode(encodedArgs, (uint24));
-
-        // Must have valid fees
-        return (fee == MINFEE || fee == MIDFEE || fee == MAXFEE);
-    }
-
     /// @inheritdoc IMigration
     function migrationStarted(address meToken)
         external
@@ -175,6 +160,21 @@ contract UniswapSingleTransferMigration is ReentrancyGuard, Vault, IMigration {
         return (usts.fee != 0 && !usts.started);
     }
 
+    /// @inheritdoc Vault
+    function isValid(bytes memory encodedArgs)
+        external
+        pure
+        override
+        returns (bool)
+    {
+        // encodedArgs empty
+        if (encodedArgs.length == 0) return false;
+        uint24 fee = abi.decode(encodedArgs, (uint24));
+
+        // Must have valid fees
+        return (fee == MINFEE || fee == MIDFEE || fee == MAXFEE);
+    }
+
     /// @dev parent call must have reentrancy check
     function _swap(address meToken) private returns (uint256 amountOut) {
         UniswapSingleTransfer storage usts = _uniswapSingleTransfers[meToken];
diff --git a/contracts/vaults/Vault.sol b/contracts/vaults/Vault.sol
index b5012b35..7a96e7c4 100644
--- a/contracts/vaults/Vault.sol
+++ b/contracts/vaults/Vault.sol
@@ -105,7 +105,7 @@ contract Vault is IVault, ReentrancyGuard {
     /// @inheritdoc IVault
     function isValid(
         bytes memory /* encodedArgs */
-    ) external virtual override returns (bool) {
+    ) external pure virtual override returns (bool) {
         return true;
     }
 }