diff --git a/circuits/cpp/src/aztec3/circuits/abis/c_bind.cpp b/circuits/cpp/src/aztec3/circuits/abis/c_bind.cpp
index 6f4486319f4..bb4cdf82959 100644
--- a/circuits/cpp/src/aztec3/circuits/abis/c_bind.cpp
+++ b/circuits/cpp/src/aztec3/circuits/abis/c_bind.cpp
@@ -360,8 +360,9 @@ WASM_EXPORT void abis__compute_contract_leaf(uint8_t const* contract_leaf_preima
 {
     NewContractData<NT> leaf_preimage;
     read(contract_leaf_preimage_buf, leaf_preimage);
-    leaf_preimage.hash();
-    NT::fr::serialize_to_buffer(leaf_preimage.hash(), output);
+    // as per the circuit implementation, if contract address == zero then return a zero leaf
+    auto to_write = leaf_preimage.contract_address == NT::address(0) ? NT::fr(0) : leaf_preimage.hash();
+    NT::fr::serialize_to_buffer(to_write, output);
 }
 
 /* Typescript test helpers that call as_string_output() to stress serialization.
diff --git a/circuits/cpp/src/aztec3/circuits/rollup/base/.test.cpp b/circuits/cpp/src/aztec3/circuits/rollup/base/.test.cpp
index 7ede6c7b1e3..d2f266d15d5 100644
--- a/circuits/cpp/src/aztec3/circuits/rollup/base/.test.cpp
+++ b/circuits/cpp/src/aztec3/circuits/rollup/base/.test.cpp
@@ -238,7 +238,8 @@ TEST_F(base_rollup_tests, contract_leaf_inserted)
 
     // create expected end contract tree snapshot
     auto expected_contract_leaf = crypto::pedersen_hash::hash_multiple(
-        { new_contract.contract_address, new_contract.portal_contract_address, new_contract.function_tree_root });
+        { new_contract.contract_address, new_contract.portal_contract_address, new_contract.function_tree_root },
+        GeneratorIndex::CONTRACT_LEAF);
     auto expeted_end_contracts_snapshot_tree = stdlib::merkle_tree::MemoryTree(CONTRACT_TREE_HEIGHT);
     expeted_end_contracts_snapshot_tree.update_element(0, expected_contract_leaf);
 
@@ -284,7 +285,8 @@ TEST_F(base_rollup_tests, contract_leaf_inserted_in_non_empty_snapshot_tree)
 
     // create expected end contract tree snapshot
     auto expected_contract_leaf = crypto::pedersen_hash::hash_multiple(
-        { new_contract.contract_address, new_contract.portal_contract_address, new_contract.function_tree_root });
+        { new_contract.contract_address, new_contract.portal_contract_address, new_contract.function_tree_root },
+        GeneratorIndex::CONTRACT_LEAF);
     auto expeted_end_contracts_snapshot_tree = start_contract_tree_snapshot;
     expeted_end_contracts_snapshot_tree.update_element(12, expected_contract_leaf);
 
@@ -533,7 +535,8 @@ TEST_F(base_rollup_tests, calldata_hash)
         .function_tree_root = fr(2),
     };
     auto contract_leaf = crypto::pedersen_hash::hash_multiple(
-        { new_contract.contract_address, new_contract.portal_contract_address, new_contract.function_tree_root });
+        { new_contract.contract_address, new_contract.portal_contract_address, new_contract.function_tree_root },
+        GeneratorIndex::CONTRACT_LEAF);
     inputs.kernel_data[0].public_inputs.end.new_contracts[0] = new_contract;
     auto contract_leaf_buffer = contract_leaf.to_buffer();
     auto contract_address_buffer = new_contract.contract_address.to_field().to_buffer();
diff --git a/circuits/cpp/src/aztec3/circuits/rollup/base/native_base_rollup_circuit.cpp b/circuits/cpp/src/aztec3/circuits/rollup/base/native_base_rollup_circuit.cpp
index e50e0d81132..3f0f12b4a66 100644
--- a/circuits/cpp/src/aztec3/circuits/rollup/base/native_base_rollup_circuit.cpp
+++ b/circuits/cpp/src/aztec3/circuits/rollup/base/native_base_rollup_circuit.cpp
@@ -87,8 +87,8 @@ std::vector<NT::fr> calculate_contract_leaves(BaseRollupInputs baseRollupInputs)
             NT::fr function_tree_root = new_contacts[j].function_tree_root;
 
             // Pedersen hash of the 3 fields (contract_address, portal_contract_address, function_tree_root)
-            auto contract_leaf =
-                crypto::pedersen_hash::hash_multiple({ contract_address, portal_contract_address, function_tree_root });
+            auto contract_leaf = crypto::pedersen_hash::hash_multiple(
+                { contract_address, portal_contract_address, function_tree_root }, GeneratorIndex::CONTRACT_LEAF);
 
             // When there is no contract deployment, we should insert a zero leaf into the tree and ignore the
             // member-ship check. This is to ensure that we don't hit "already deployed" errors when we are not
diff --git a/circuits/cpp/src/aztec3/circuits/rollup/root/.test.cpp b/circuits/cpp/src/aztec3/circuits/rollup/root/.test.cpp
index 0fa7fb8976e..0f338199031 100644
--- a/circuits/cpp/src/aztec3/circuits/rollup/root/.test.cpp
+++ b/circuits/cpp/src/aztec3/circuits/rollup/root/.test.cpp
@@ -279,7 +279,8 @@ TEST_F(root_rollup_tests, almost_full_root)
     };
     base_inputs_2.kernel_data[0].public_inputs.end.new_contracts[0] = new_contract;
     auto contract_leaf = crypto::pedersen_hash::hash_multiple(
-        { new_contract.contract_address, new_contract.portal_contract_address, new_contract.function_tree_root });
+        { new_contract.contract_address, new_contract.portal_contract_address, new_contract.function_tree_root },
+        GeneratorIndex::CONTRACT_LEAF);
     contract_tree.update_element(0, contract_leaf);
 
     base_inputs_2.new_contracts_subtree_sibling_path =