diff --git a/contracts/WakuRlnRegistry.sol b/contracts/WakuRlnRegistry.sol
index 6960d2b..9f944fa 100644
--- a/contracts/WakuRlnRegistry.sol
+++ b/contracts/WakuRlnRegistry.sol
@@ -48,7 +48,7 @@ contract WakuRlnRegistry is Ownable {
         _insertIntoStorageMap(address(newStorageContract));
     }
 
-    function register(uint256[] calldata commitments) external payable onlyUsableStorage {
+    function register(uint256[] calldata commitments) external onlyUsableStorage {
         // iteratively check if the storage contract is full, and increment the usingStorageIndex if it is
         while (true) {
             try WakuRln(storages[usingStorageIndex]).register(commitments) {
@@ -67,12 +67,12 @@ contract WakuRlnRegistry is Ownable {
         }
     }
 
-    function register(uint16 storageIndex, uint256[] calldata commitments) external payable {
+    function register(uint16 storageIndex, uint256[] calldata commitments) external {
         if (storageIndex >= nextStorageIndex) revert NoStorageContractAvailable();
         WakuRln(storages[storageIndex]).register(commitments);
     }
 
-    function register(uint16 storageIndex, uint256 commitment) external payable {
+    function register(uint16 storageIndex, uint256 commitment) external {
         if (storageIndex >= nextStorageIndex) revert NoStorageContractAvailable();
         // optimize the gas used below
         uint256[] memory commitments = new uint256[](1);
diff --git a/docs/index.md b/docs/index.md
index 1bb0cc2..a965d33 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -181,19 +181,19 @@ function newStorage() external
 ### register
 
 ```solidity
-function register(uint256[] commitments) external payable
+function register(uint256[] commitments) external
 ```
 
 ### register
 
 ```solidity
-function register(uint16 storageIndex, uint256[] commitments) external payable
+function register(uint16 storageIndex, uint256[] commitments) external
 ```
 
 ### register
 
 ```solidity
-function register(uint16 storageIndex, uint256 commitment) external payable
+function register(uint16 storageIndex, uint256 commitment) external
 ```
 
 ### forceProgress