diff --git a/packages/evm/contracts/adapters/DendrETH/DendrETHAdapter.sol b/packages/evm/contracts/adapters/DendrETH/DendrETHAdapter.sol
index 87e29bb2..24e9a2fb 100644
--- a/packages/evm/contracts/adapters/DendrETH/DendrETHAdapter.sol
+++ b/packages/evm/contracts/adapters/DendrETH/DendrETHAdapter.sol
@@ -8,6 +8,7 @@ import { BlockHashOracleAdapter } from "../BlockHashOracleAdapter.sol";
 contract DendrETHAdapter is BlockHashOracleAdapter {
     error InvalidUpdate();
     error BlockHeaderNotAvailable(uint256 slot);
+    error InvalidSlot();
     error InvalidBlockNumberProof();
     error InvalidBlockHashProof();
 
@@ -22,6 +23,8 @@ contract DendrETHAdapter is BlockHashOracleAdapter {
     function storeBlockHeader(
         uint32 _chainId,
         uint64 _slot,
+        bytes32[] calldata _slotProof,
+        bytes32 _finalizedBlockHeader,
         uint256 _blockNumber,
         bytes32[] calldata _blockNumberProof,
         bytes32 _blockHash,
@@ -34,7 +37,7 @@ contract DendrETHAdapter is BlockHashOracleAdapter {
         bool found = false;
 
         do {
-            if (_slot == lightClient.optimisticSlots(i)) {
+            if (_finalizedBlockHeader == lightClient.finalizedHeaders(i)) {
                 found = true;
                 break;
             }
@@ -48,13 +51,15 @@ contract DendrETHAdapter is BlockHashOracleAdapter {
             revert BlockHeaderNotAvailable(_slot);
         }
 
-        bytes32 blockHeaderRoot = lightClient.optimisticHeaders(i);
+        if (!SSZ.verifySlot(_slot, _slotProof, _finalizedBlockHeader)) {
+            revert InvalidSlot();
+        }
 
-        if (!SSZ.verifyBlockNumber(_blockNumber, _blockNumberProof, blockHeaderRoot)) {
+        if (!SSZ.verifyBlockNumber(_blockNumber, _blockNumberProof, _finalizedBlockHeader)) {
             revert InvalidBlockNumberProof();
         }
 
-        if (!SSZ.verifyBlockHash(_blockHash, _blockHashProof, blockHeaderRoot)) {
+        if (!SSZ.verifyBlockHash(_blockHash, _blockHashProof, _finalizedBlockHeader)) {
             revert InvalidBlockHashProof();
         }
 
@@ -66,6 +71,7 @@ contract DendrETHAdapter is BlockHashOracleAdapter {
     function storeBlockHeader(
         uint32 _chainId,
         uint64 _slot,
+        bytes32[] calldata _slotProof,
         uint256 _blockNumber,
         bytes32[] calldata _blockNumberProof,
         bytes32 _blockHash,
@@ -76,17 +82,17 @@ contract DendrETHAdapter is BlockHashOracleAdapter {
 
         lightClient.light_client_update(update);
 
-        if (lightClient.optimisticHeaderSlot() != _slot) {
+        bytes32 finalizedHeaderRoot = lightClient.finalizedHeaderRoot();
+
+        if (!SSZ.verifySlot(_slot, _slotProof, finalizedHeaderRoot)) {
             revert InvalidUpdate();
         }
 
-        bytes32 blockHeaderRoot = lightClient.optimisticHeaderRoot();
-
-        if (!SSZ.verifyBlockNumber(_blockNumber, _blockNumberProof, blockHeaderRoot)) {
+        if (!SSZ.verifyBlockNumber(_blockNumber, _blockNumberProof, finalizedHeaderRoot)) {
             revert InvalidBlockNumberProof();
         }
 
-        if (!SSZ.verifyBlockHash(_blockHash, _blockHashProof, blockHeaderRoot)) {
+        if (!SSZ.verifyBlockHash(_blockHash, _blockHashProof, finalizedHeaderRoot)) {
             revert InvalidBlockHashProof();
         }
 
diff --git a/packages/evm/contracts/adapters/DendrETH/interfaces/IDendrETH.sol b/packages/evm/contracts/adapters/DendrETH/interfaces/IDendrETH.sol
index a4e98267..c198d362 100644
--- a/packages/evm/contracts/adapters/DendrETH/interfaces/IDendrETH.sol
+++ b/packages/evm/contracts/adapters/DendrETH/interfaces/IDendrETH.sol
@@ -14,13 +14,9 @@ struct LightClientUpdate {
 interface ILightClient {
     function currentIndex() external view returns (uint256);
 
-    function optimisticHeaders(uint256 index) external view returns (bytes32);
+    function finalizedHeaders(uint256 index) external view returns (bytes32);
 
-    function optimisticHeaderRoot() external view returns (bytes32);
-
-    function optimisticSlots(uint256 index) external view returns (uint256);
-
-    function optimisticHeaderSlot() external view returns (uint256);
+    function finalizedHeaderRoot() external view returns (bytes32);
 
     function light_client_update(LightClientUpdate calldata update) external;
 }
diff --git a/packages/evm/contracts/adapters/Telepathy/libraries/SimpleSerialize.sol b/packages/evm/contracts/adapters/Telepathy/libraries/SimpleSerialize.sol
index 3ba3f9d3..a4fc6f64 100644
--- a/packages/evm/contracts/adapters/Telepathy/libraries/SimpleSerialize.sol
+++ b/packages/evm/contracts/adapters/Telepathy/libraries/SimpleSerialize.sol
@@ -6,6 +6,9 @@ library SSZ {
     uint256 internal constant EXECUTION_PAYLOAD_BLOCK_NUMBER_INDEX = 3222;
     uint256 internal constant EXECUTION_PAYLOAD_BLOCK_HASH_INDEX = 3228;
 
+    // G-index for the BeaconBlockHeader -> slot
+    uint256 internal constant SLOT_INDEX = 8;
+
     function toLittleEndian(uint256 _v) internal pure returns (bytes32) {
         _v =
             ((_v & 0xFF00FF00FF00FF00FF00FF00FF00FF00FF00FF00FF00FF00FF00FF00FF00FF00) >> 8) |
@@ -74,4 +77,8 @@ library SSZ {
     ) internal pure returns (bool) {
         return isValidMerkleBranch(_blockHash, EXECUTION_PAYLOAD_BLOCK_HASH_INDEX, _blockHashProof, _headerRoot);
     }
+
+    function verifySlot(uint256 _slot, bytes32[] memory _slotProof, bytes32 _headerRoot) internal pure returns (bool) {
+        return isValidMerkleBranch(toLittleEndian(_slot), SLOT_INDEX, _slotProof, _headerRoot);
+    }
 }