diff --git a/contracts/contracts/Poll.sol b/contracts/contracts/Poll.sol
index 800d68adf2..d7f163df14 100644
--- a/contracts/contracts/Poll.sol
+++ b/contracts/contracts/Poll.sol
@@ -163,7 +163,7 @@ contract Poll is Params, Utilities, SnarkCommon, Ownable, EmptyBallotRoots, IPol
   }
 
   /// @inheritdoc IPoll
-  function publishMessage(Message calldata _message, PubKey calldata _encPubKey) public virtual isWithinVotingDeadline {
+  function publishMessage(Message memory _message, PubKey calldata _encPubKey) public virtual isWithinVotingDeadline {
     // we check that we do not exceed the max number of messages
     if (numMessages == maxValues.maxMessages) revert TooManyMessages();
 
@@ -177,6 +177,10 @@ contract Poll is Params, Utilities, SnarkCommon, Ownable, EmptyBallotRoots, IPol
       numMessages++;
     }
 
+    // we enforce that msgType here is 1 so we don't need checks
+    // at the circuit level
+    _message.msgType = 1;
+
     uint256 messageLeaf = hashMessageAndEncPubKey(_message, _encPubKey);
     extContracts.messageAq.enqueue(messageLeaf);
 
diff --git a/contracts/contracts/interfaces/IPoll.sol b/contracts/contracts/interfaces/IPoll.sol
index c53e44dd28..4a3b1ac94b 100644
--- a/contracts/contracts/interfaces/IPoll.sol
+++ b/contracts/contracts/interfaces/IPoll.sol
@@ -25,7 +25,7 @@ interface IPoll {
   /// @param _encPubKey An epheremal public key which can be combined with the
   /// coordinator's private key to generate an ECDH shared key with which
   /// to encrypt the message.
-  function publishMessage(DomainObjs.Message calldata _message, DomainObjs.PubKey calldata _encPubKey) external;
+  function publishMessage(DomainObjs.Message memory _message, DomainObjs.PubKey calldata _encPubKey) external;
 
   /// @notice The first step of merging the MACI state AccQueue. This allows the
   /// ProcessMessages circuit to access the latest state tree and ballots via