diff --git a/l1-contracts/src/core/libraries/Errors.sol b/l1-contracts/src/core/libraries/Errors.sol
index 1c3473ec5148..f873d0ace2bd 100644
--- a/l1-contracts/src/core/libraries/Errors.sol
+++ b/l1-contracts/src/core/libraries/Errors.sol
@@ -73,7 +73,6 @@ library Errors {
   error Rollup__TryingToProveNonExistingBlock(); // 0x34ef4954
   error Rollup__UnavailableTxs(bytes32 txsHash); // 0x414906c3
   error Rollup__NonZeroDaFee(); // 0xd9c75f52
-  error Rollup__NonZeroL2Fee(); // 0x7e728abc
   error Rollup__InvalidBasisPointFee(uint256 basisPointFee); // 0x4292d136
   error Rollup__InvalidManaBaseFee(uint256 expected, uint256 actual); // 0x73b6d896
   error Rollup__StartAndEndNotSameEpoch(Epoch start, Epoch end);
diff --git a/l1-contracts/src/core/libraries/RollupLibs/FeeMath.sol b/l1-contracts/src/core/libraries/RollupLibs/FeeMath.sol
index f9c7bfc3e9b6..47a4e035fc80 100644
--- a/l1-contracts/src/core/libraries/RollupLibs/FeeMath.sol
+++ b/l1-contracts/src/core/libraries/RollupLibs/FeeMath.sol
@@ -22,6 +22,7 @@ uint256 constant CONGESTION_UPDATE_FRACTION = 854700854;
 
 uint256 constant BLOB_GAS_PER_BLOB = 2 ** 17;
 uint256 constant GAS_PER_BLOB_POINT_EVALUATION = 50_000;
+uint256 constant BLOBS_PER_BLOCK = 3;
 
 struct OracleInput {
   int256 feeAssetPriceModifier;
@@ -116,9 +117,11 @@ library FeeMath {
     );
 
     EthValue dataCostPerMana = EthValue.wrap(
-      Math.mulDiv(3 * BLOB_GAS_PER_BLOB, _fees.blobFee, MANA_TARGET, Math.Rounding.Ceil)
+      Math.mulDiv(
+        BLOBS_PER_BLOCK * BLOB_GAS_PER_BLOB, _fees.blobFee, MANA_TARGET, Math.Rounding.Ceil
+      )
     );
-    uint256 gasUsed = L1_GAS_PER_BLOCK_PROPOSED + 3 * GAS_PER_BLOB_POINT_EVALUATION
+    uint256 gasUsed = L1_GAS_PER_BLOCK_PROPOSED + BLOBS_PER_BLOCK * GAS_PER_BLOB_POINT_EVALUATION
       + L1_GAS_PER_EPOCH_VERIFIED / _epochDuration;
     EthValue gasCostPerMana =
       EthValue.wrap(Math.mulDiv(gasUsed, _fees.baseFee, MANA_TARGET, Math.Rounding.Ceil));
diff --git a/l1-contracts/src/core/libraries/RollupLibs/ProposeLib.sol b/l1-contracts/src/core/libraries/RollupLibs/ProposeLib.sol
index 32f67e228332..1f2e5f3d5a0f 100644
--- a/l1-contracts/src/core/libraries/RollupLibs/ProposeLib.sol
+++ b/l1-contracts/src/core/libraries/RollupLibs/ProposeLib.sol
@@ -158,9 +158,21 @@ library ProposeLib {
     view
     returns (ManaBaseFeeComponents memory)
   {
-    // @todo If we are not canonical we can just return mostly zeros here.
-
     RollupStore storage rollupStore = STFLib.getStorage();
+
+    // If we are not the canonical rollup, we cannot claim any fees, so we return 0s
+    // The congestion multiplier could be computed, but as it could only be used to guide
+    // might as well save the gas and anyone interested can do it off-chain.
+    if (address(this) != rollupStore.config.feeAssetPortal.canonicalRollup()) {
+      return ManaBaseFeeComponents({
+        congestionCost: 0,
+        provingCost: 0,
+        congestionMultiplier: 0,
+        dataCost: 0,
+        gasCost: 0
+      });
+    }
+
     // If we can prune, we use the proven block, otherwise the pending block
     uint256 blockOfInterest = STFLib.canPruneAtTime(_timestamp)
       ? rollupStore.tips.provenBlockNumber
@@ -275,19 +287,13 @@ library ProposeLib {
       Errors.Rollup__UnavailableTxs(_args.header.contentCommitment.blobsHash)
     );
 
-    // If not canonical rollup, require that the fees are zero
-    if (address(this) != rollupStore.config.feeAssetPortal.canonicalRollup()) {
-      require(_args.header.globalVariables.gasFees.feePerDaGas == 0, Errors.Rollup__NonZeroDaFee());
-      require(_args.header.globalVariables.gasFees.feePerL2Gas == 0, Errors.Rollup__NonZeroL2Fee());
-    } else {
-      require(_args.header.globalVariables.gasFees.feePerDaGas == 0, Errors.Rollup__NonZeroDaFee());
-      require(
-        _args.header.globalVariables.gasFees.feePerL2Gas == _args.manaBaseFee,
-        Errors.Rollup__InvalidManaBaseFee(
-          _args.manaBaseFee, _args.header.globalVariables.gasFees.feePerL2Gas
-        )
-      );
-    }
+    require(_args.header.globalVariables.gasFees.feePerDaGas == 0, Errors.Rollup__NonZeroDaFee());
+    require(
+      _args.header.globalVariables.gasFees.feePerL2Gas == _args.manaBaseFee,
+      Errors.Rollup__InvalidManaBaseFee(
+        _args.manaBaseFee, _args.header.globalVariables.gasFees.feePerL2Gas
+      )
+    );
   }
 
   /**
diff --git a/l1-contracts/test/Rollup.t.sol b/l1-contracts/test/Rollup.t.sol
index a1153e990c7d..579d615696ce 100644
--- a/l1-contracts/test/Rollup.t.sol
+++ b/l1-contracts/test/Rollup.t.sol
@@ -335,7 +335,8 @@ contract RollupTest is RollupBase {
 
     skipBlobCheck(address(rollup));
 
-    vm.expectRevert(abi.encodeWithSelector(Errors.Rollup__NonZeroL2Fee.selector));
+    // When not canonical, we expect the fee to be 0
+    vm.expectRevert(abi.encodeWithSelector(Errors.Rollup__InvalidManaBaseFee.selector, 0, 1));
     ProposeArgs memory args = ProposeArgs({
       header: header,
       archive: data.archive,