diff --git a/barretenberg/cpp/src/barretenberg/dsl/acir_format/acir_format.test.cpp b/barretenberg/cpp/src/barretenberg/dsl/acir_format/acir_format.test.cpp
index eff4e6928ae3..2aa6557b03f9 100644
--- a/barretenberg/cpp/src/barretenberg/dsl/acir_format/acir_format.test.cpp
+++ b/barretenberg/cpp/src/barretenberg/dsl/acir_format/acir_format.test.cpp
@@ -79,24 +79,24 @@ TEST_F(AcirFormatTests, TestLogicGateFromNoirCircuit)
      * }
      **/
     RangeConstraint range_a{
-        .witness = 1,
+        .witness = 0,
         .num_bits = 32,
     };
     RangeConstraint range_b{
-        .witness = 2,
+        .witness = 1,
         .num_bits = 32,
     };
 
     LogicConstraint logic_constraint{
-        .a = 1,
-        .b = 2,
-        .result = 3,
+        .a = 0,
+        .b = 1,
+        .result = 2,
         .num_bits = 32,
         .is_xor_gate = 1,
     };
     poly_triple expr_a{
-        .a = 3,
-        .b = 4,
+        .a = 2,
+        .b = 3,
         .c = 0,
         .q_m = 0,
         .q_l = 1,
@@ -105,9 +105,9 @@ TEST_F(AcirFormatTests, TestLogicGateFromNoirCircuit)
         .q_c = -10,
     };
     poly_triple expr_b{
-        .a = 4,
-        .b = 5,
-        .c = 6,
+        .a = 3,
+        .b = 4,
+        .c = 5,
         .q_m = 1,
         .q_l = 0,
         .q_r = 0,
@@ -115,9 +115,9 @@ TEST_F(AcirFormatTests, TestLogicGateFromNoirCircuit)
         .q_c = 0,
     };
     poly_triple expr_c{
-        .a = 4,
-        .b = 6,
-        .c = 4,
+        .a = 3,
+        .b = 5,
+        .c = 3,
         .q_m = 1,
         .q_l = 0,
         .q_r = 0,
@@ -126,7 +126,7 @@ TEST_F(AcirFormatTests, TestLogicGateFromNoirCircuit)
 
     };
     poly_triple expr_d{
-        .a = 6,
+        .a = 5,
         .b = 0,
         .c = 0,
         .q_m = 0,
@@ -139,8 +139,8 @@ TEST_F(AcirFormatTests, TestLogicGateFromNoirCircuit)
     // EXPR [ (1, _4, _6) (-1, _4) 0 ]
     // EXPR [ (-1, _6) 1 ]
 
-    acir_format constraint_system{ .varnum = 7,
-                                   .public_inputs = { 2 },
+    acir_format constraint_system{ .varnum = 6,
+                                   .public_inputs = { 1 },
                                    .logic_constraints = { logic_constraint },
                                    .range_constraints = { range_a, range_b },
                                    .sha256_constraints = {},
@@ -181,13 +181,13 @@ TEST_F(AcirFormatTests, TestSchnorrVerifyPass)
     std::vector<RangeConstraint> range_constraints;
     for (uint32_t i = 0; i < 10; i++) {
         range_constraints.push_back(RangeConstraint{
-            .witness = i + 1,
+            .witness = i,
             .num_bits = 15,
         });
     }
 
     std::vector<uint32_t> signature(64);
-    for (uint32_t i = 0, value = 13; i < 64; i++, value++) {
+    for (uint32_t i = 0, value = 12; i < 64; i++, value++) {
         signature[i] = value;
         range_constraints.push_back(RangeConstraint{
             .witness = value,
@@ -196,13 +196,13 @@ TEST_F(AcirFormatTests, TestSchnorrVerifyPass)
     }
 
     SchnorrConstraint schnorr_constraint{
-        .message = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 },
-        .public_key_x = 11,
-        .public_key_y = 12,
-        .result = 77,
+        .message = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 },
+        .public_key_x = 10,
+        .public_key_y = 11,
+        .result = 76,
         .signature = signature,
     };
-    acir_format constraint_system{ .varnum = 82,
+    acir_format constraint_system{ .varnum = 81,
                                    .public_inputs = {},
                                    .logic_constraints = {},
                                    .range_constraints = range_constraints,
@@ -271,13 +271,13 @@ TEST_F(AcirFormatTests, TestSchnorrVerifySmallRange)
     std::vector<RangeConstraint> range_constraints;
     for (uint32_t i = 0; i < 10; i++) {
         range_constraints.push_back(RangeConstraint{
-            .witness = i + 1,
+            .witness = i,
             .num_bits = 8,
         });
     }
 
     std::vector<uint32_t> signature(64);
-    for (uint32_t i = 0, value = 13; i < 64; i++, value++) {
+    for (uint32_t i = 0, value = 12; i < 64; i++, value++) {
         signature[i] = value;
         range_constraints.push_back(RangeConstraint{
             .witness = value,
@@ -286,14 +286,14 @@ TEST_F(AcirFormatTests, TestSchnorrVerifySmallRange)
     }
 
     SchnorrConstraint schnorr_constraint{
-        .message = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 },
-        .public_key_x = 11,
-        .public_key_y = 12,
-        .result = 77,
+        .message = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 },
+        .public_key_x = 10,
+        .public_key_y = 11,
+        .result = 76,
         .signature = signature,
     };
     acir_format constraint_system{
-        .varnum = 82,
+        .varnum = 81,
         .public_inputs = {},
         .logic_constraints = {},
         .range_constraints = range_constraints,
@@ -360,39 +360,39 @@ TEST_F(AcirFormatTests, TestSchnorrVerifySmallRange)
 TEST_F(AcirFormatTests, TestVarKeccak)
 {
     HashInput input1;
-    input1.witness = 1;
+    input1.witness = 0;
     input1.num_bits = 8;
     HashInput input2;
-    input2.witness = 2;
+    input2.witness = 1;
     input2.num_bits = 8;
     HashInput input3;
-    input3.witness = 3;
+    input3.witness = 2;
     input3.num_bits = 8;
     KeccakVarConstraint keccak;
     keccak.inputs = { input1, input2, input3 };
-    keccak.var_message_size = 4;
-    keccak.result = { 5,  6,  7,  8,  9,  10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
-                      21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36 };
+    keccak.var_message_size = 3;
+    keccak.result = { 4,  5,  6,  7,  8,  9,  10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
+                      20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35 };
 
     RangeConstraint range_a{
-        .witness = 1,
+        .witness = 0,
         .num_bits = 8,
     };
     RangeConstraint range_b{
-        .witness = 2,
+        .witness = 1,
         .num_bits = 8,
     };
     RangeConstraint range_c{
-        .witness = 3,
+        .witness = 2,
         .num_bits = 8,
     };
     RangeConstraint range_d{
-        .witness = 4,
+        .witness = 3,
         .num_bits = 8,
     };
 
     auto dummy = poly_triple{
-        .a = 1,
+        .a = 0,
         .b = 0,
         .c = 0,
         .q_m = 0,
@@ -403,7 +403,7 @@ TEST_F(AcirFormatTests, TestVarKeccak)
     };
 
     acir_format constraint_system{
-        .varnum = 37,
+        .varnum = 36,
         .public_inputs = {},
         .logic_constraints = {},
         .range_constraints = { range_a, range_b, range_c, range_d },
diff --git a/barretenberg/cpp/src/barretenberg/dsl/acir_format/acir_to_constraint_buf.hpp b/barretenberg/cpp/src/barretenberg/dsl/acir_format/acir_to_constraint_buf.hpp
index 491c2e79de4d..d1ebbb6b89f3 100644
--- a/barretenberg/cpp/src/barretenberg/dsl/acir_format/acir_to_constraint_buf.hpp
+++ b/barretenberg/cpp/src/barretenberg/dsl/acir_format/acir_to_constraint_buf.hpp
@@ -29,12 +29,12 @@ namespace acir_format {
  */
 poly_triple serialize_arithmetic_gate(Circuit::Expression const& arg)
 {
-    // TODO(https://github.com/AztecProtocol/barretenberg/issues/816): Instead of zeros for a,b,c, what we really want
-    // is something like the bberg zero_idx. Hardcoding these to 0 has the same effect only if zero_idx == 0, as has
-    // historically been the case. If that changes, this might break since now "0" points to some non-zero witness in
-    // variables. (From some testing, it seems like it may not break but only because the selectors multiplying the
-    // erroneously non-zero value are zero. Still, it seems like a bad idea to have erroneous wire values even if they
-    // dont break the relation. They'll still add cost in commitments, for example).
+    // TODO(https://github.com/AztecProtocol/barretenberg/issues/816): The initialization of the witness indices a,b,c
+    // to 0 is implicitly assuming that (builder.zero_idx == 0) which is no longer the case. Now, witness idx 0 in
+    // general will correspond to some non-zero value and some witnesses which are not explicitly set below will be
+    // erroneously populated with this value. This does not cause failures however because the corresponding selector
+    // will indeed be 0 so the gate will be satisfied. Still, its a bad idea to have erroneous wire values
+    // even if they dont break the relation. They'll still add cost in commitments, for example.
     poly_triple pt{
         .a = 0,
         .b = 0,
@@ -72,8 +72,8 @@ poly_triple serialize_arithmetic_gate(Circuit::Expression const& arg)
         // If the witness index has not yet been set or if the corresponding linear term is active, set the witness
         // index and the corresponding selector value.
         // TODO(https://github.com/AztecProtocol/barretenberg/issues/816): May need to adjust the pt.a == witness_idx
-        // check (and the others like it) since we initialize a,b,c with 0 but 0 becomes a valid witness index if the +1
-        // offset is removed from noir.
+        // check (and the others like it) since we initialize a,b,c with 0 but 0 is a valid witness index once the
+        // +1 offset is removed from noir.
         if (!a_set || pt.a == witness_idx) { // q_l * w_l
             pt.a = witness_idx;
             pt.q_l = selector_value;
@@ -294,7 +294,8 @@ acir_format circuit_buf_to_acir_format(std::vector<uint8_t> const& buf)
     auto circuit = Circuit::Circuit::bincodeDeserialize(buf);
 
     acir_format af;
-    af.varnum = circuit.current_witness_index;
+    // `varnum` is the true number of variables, thus we add one to the index which starts at zero
+    af.varnum = circuit.current_witness_index + 1;
     af.public_inputs = join({ map(circuit.public_parameters.value, [](auto e) { return e.value; }),
                               map(circuit.return_values.value, [](auto e) { return e.value; }) });
     std::map<uint32_t, BlockConstraint> block_id_to_block_constraint;
@@ -340,9 +341,7 @@ WitnessVector witness_buf_to_witness_data(std::vector<uint8_t> const& buf)
 {
     auto w = WitnessMap::WitnessMap::bincodeDeserialize(buf);
     WitnessVector wv;
-    // TODO(https://github.com/AztecProtocol/barretenberg/issues/816): Does "index" need to be initialized to 0 once we
-    // get rid of the +1 offset in noir?
-    size_t index = 1;
+    size_t index = 0;
     for (auto& e : w.value) {
         // ACIR uses a sparse format for WitnessMap where unused witness indices may be left unassigned.
         // To ensure that witnesses sit at the correct indices in the `WitnessVector`, we fill any indices
diff --git a/barretenberg/cpp/src/barretenberg/dsl/acir_format/block_constraint.test.cpp b/barretenberg/cpp/src/barretenberg/dsl/acir_format/block_constraint.test.cpp
index 4451cfb7956e..526eabed4812 100644
--- a/barretenberg/cpp/src/barretenberg/dsl/acir_format/block_constraint.test.cpp
+++ b/barretenberg/cpp/src/barretenberg/dsl/acir_format/block_constraint.test.cpp
@@ -14,13 +14,13 @@ class UltraPlonkRAM : public ::testing::Test {
 };
 size_t generate_block_constraint(BlockConstraint& constraint, WitnessVector& witness_values)
 {
-    size_t witness_len = 1;
+    size_t witness_len = 0;
     witness_values.emplace_back(1);
     witness_len++;
 
     fr two = fr::one() + fr::one();
     poly_triple a0 = poly_triple{
-        .a = 1,
+        .a = 0,
         .b = 0,
         .c = 0,
         .q_m = 0,
@@ -41,7 +41,7 @@ size_t generate_block_constraint(BlockConstraint& constraint, WitnessVector& wit
         .q_c = three,
     };
     poly_triple r1 = poly_triple{
-        .a = 1,
+        .a = 0,
         .b = 0,
         .c = 0,
         .q_m = 0,
@@ -51,7 +51,7 @@ size_t generate_block_constraint(BlockConstraint& constraint, WitnessVector& wit
         .q_c = fr::neg_one(),
     };
     poly_triple r2 = poly_triple{
-        .a = 1,
+        .a = 0,
         .b = 0,
         .c = 0,
         .q_m = 0,
@@ -61,7 +61,7 @@ size_t generate_block_constraint(BlockConstraint& constraint, WitnessVector& wit
         .q_c = fr::neg_one(),
     };
     poly_triple y = poly_triple{
-        .a = 2,
+        .a = 1,
         .b = 0,
         .c = 0,
         .q_m = 0,
@@ -73,7 +73,7 @@ size_t generate_block_constraint(BlockConstraint& constraint, WitnessVector& wit
     witness_values.emplace_back(2);
     witness_len++;
     poly_triple z = poly_triple{
-        .a = 3,
+        .a = 2,
         .b = 0,
         .c = 0,
         .q_m = 0,
diff --git a/barretenberg/cpp/src/barretenberg/dsl/acir_format/ecdsa_secp256k1.test.cpp b/barretenberg/cpp/src/barretenberg/dsl/acir_format/ecdsa_secp256k1.test.cpp
index c5ce13927801..be404915e22d 100644
--- a/barretenberg/cpp/src/barretenberg/dsl/acir_format/ecdsa_secp256k1.test.cpp
+++ b/barretenberg/cpp/src/barretenberg/dsl/acir_format/ecdsa_secp256k1.test.cpp
@@ -40,7 +40,7 @@ size_t generate_ecdsa_constraint(EcdsaSecp256k1Constraint& ecdsa_constraint, Wit
     std::vector<uint32_t> pub_x_indices_in;
     std::vector<uint32_t> pub_y_indices_in;
     std::vector<uint32_t> signature_in;
-    size_t offset = 1;
+    size_t offset = 0;
     for (size_t i = 0; i < hashed_message.size(); ++i) {
         message_in.emplace_back(i + offset);
         const auto byte = static_cast<uint8_t>(hashed_message[i]);
diff --git a/barretenberg/cpp/src/barretenberg/dsl/acir_format/ecdsa_secp256r1.test.cpp b/barretenberg/cpp/src/barretenberg/dsl/acir_format/ecdsa_secp256r1.test.cpp
index 0c9b56e37fed..a87876e87892 100644
--- a/barretenberg/cpp/src/barretenberg/dsl/acir_format/ecdsa_secp256r1.test.cpp
+++ b/barretenberg/cpp/src/barretenberg/dsl/acir_format/ecdsa_secp256r1.test.cpp
@@ -23,7 +23,7 @@ size_t generate_r1_constraints(EcdsaSecp256r1Constraint& ecdsa_r1_constraint,
     std::vector<uint32_t> pub_x_indices_in;
     std::vector<uint32_t> pub_y_indices_in;
     std::vector<uint32_t> signature_in;
-    size_t offset = 1;
+    size_t offset = 0;
     for (size_t i = 0; i < hashed_message.size(); ++i) {
         message_in.emplace_back(i + offset);
         const auto byte = static_cast<uint8_t>(hashed_message[i]);
diff --git a/barretenberg/cpp/src/barretenberg/dsl/acir_format/recursion_constraint.test.cpp b/barretenberg/cpp/src/barretenberg/dsl/acir_format/recursion_constraint.test.cpp
index 170734597794..4e8e53ff3272 100644
--- a/barretenberg/cpp/src/barretenberg/dsl/acir_format/recursion_constraint.test.cpp
+++ b/barretenberg/cpp/src/barretenberg/dsl/acir_format/recursion_constraint.test.cpp
@@ -24,24 +24,24 @@ Builder create_inner_circuit()
      * }
      **/
     RangeConstraint range_a{
-        .witness = 1,
+        .witness = 0,
         .num_bits = 32,
     };
     RangeConstraint range_b{
-        .witness = 2,
+        .witness = 1,
         .num_bits = 32,
     };
 
     LogicConstraint logic_constraint{
-        .a = 1,
-        .b = 2,
-        .result = 3,
+        .a = 0,
+        .b = 1,
+        .result = 2,
         .num_bits = 32,
         .is_xor_gate = 1,
     };
     poly_triple expr_a{
-        .a = 3,
-        .b = 4,
+        .a = 2,
+        .b = 3,
         .c = 0,
         .q_m = 0,
         .q_l = 1,
@@ -50,9 +50,9 @@ Builder create_inner_circuit()
         .q_c = -10,
     };
     poly_triple expr_b{
-        .a = 4,
-        .b = 5,
-        .c = 6,
+        .a = 3,
+        .b = 4,
+        .c = 5,
         .q_m = 1,
         .q_l = 0,
         .q_r = 0,
@@ -60,9 +60,9 @@ Builder create_inner_circuit()
         .q_c = 0,
     };
     poly_triple expr_c{
-        .a = 4,
-        .b = 6,
-        .c = 4,
+        .a = 3,
+        .b = 5,
+        .c = 3,
         .q_m = 1,
         .q_l = 0,
         .q_r = 0,
@@ -71,7 +71,7 @@ Builder create_inner_circuit()
 
     };
     poly_triple expr_d{
-        .a = 6,
+        .a = 5,
         .b = 0,
         .c = 0,
         .q_m = 0,
@@ -81,8 +81,8 @@ Builder create_inner_circuit()
         .q_c = 1,
     };
 
-    acir_format constraint_system{ .varnum = 7,
-                                   .public_inputs = { 2, 3 },
+    acir_format constraint_system{ .varnum = 6,
+                                   .public_inputs = { 1, 2 },
                                    .logic_constraints = { logic_constraint },
                                    .range_constraints = { range_a, range_b },
                                    .sha256_constraints = {},
@@ -122,8 +122,7 @@ Builder create_outer_circuit(std::vector<Builder>& inner_circuits)
 {
     std::vector<RecursionConstraint> recursion_constraints;
 
-    // witness count starts at 1 (Composer reserves 1st witness to be the zero-valued zero_idx)
-    size_t witness_offset = 1;
+    size_t witness_offset = 0;
     std::array<uint32_t, RecursionConstraint::AGGREGATION_OBJECT_SIZE> output_aggregation_object;
     std::vector<fr, ContainerSlabAllocator<fr>> witness;
 
@@ -226,7 +225,7 @@ Builder create_outer_circuit(std::vector<Builder>& inner_circuits)
         // then we could get a segmentation fault as `inner_public_inputs` was never filled with values.
         if (!has_nested_proof) {
             for (size_t i = 0; i < num_inner_public_inputs; ++i) {
-                witness[inner_public_inputs[i] - 1] = inner_public_input_values[i];
+                witness[inner_public_inputs[i]] = inner_public_input_values[i];
             }
         }
 
@@ -234,7 +233,7 @@ Builder create_outer_circuit(std::vector<Builder>& inner_circuits)
         circuit_idx++;
     }
 
-    acir_format constraint_system{ .varnum = static_cast<uint32_t>(witness.size() + 1),
+    acir_format constraint_system{ .varnum = static_cast<uint32_t>(witness.size()),
                                    .public_inputs = {},
                                    .logic_constraints = {},
                                    .range_constraints = {},
diff --git a/barretenberg/cpp/src/barretenberg/dsl/acir_proofs/acir_composer.cpp b/barretenberg/cpp/src/barretenberg/dsl/acir_proofs/acir_composer.cpp
index c1ce11576f1f..3a36a3595918 100644
--- a/barretenberg/cpp/src/barretenberg/dsl/acir_proofs/acir_composer.cpp
+++ b/barretenberg/cpp/src/barretenberg/dsl/acir_proofs/acir_composer.cpp
@@ -64,20 +64,10 @@ std::vector<uint8_t> AcirComposer::create_proof(bool is_recursive)
 void AcirComposer::create_goblin_circuit(acir_format::acir_format& constraint_system,
                                          acir_format::WitnessVector& witness)
 {
-    // TODO(https://github.com/AztecProtocol/barretenberg/issues/816): The public inputs in constraint_system do not
-    // index into "witness" but rather into the future "variables" which it assumes will be equal to witness but with a
-    // prepended zero. We want to remove this +1 so that public_inputs properly indexes into witness because we're about
-    // to make calls like add_variable(witness[public_inputs[idx]]). Once the +1 is removed from noir, this correction
-    // can be removed entirely and we can use constraint_system.public_inputs directly.
-    const uint32_t pre_applied_noir_offset = 1;
-    std::vector<uint32_t> corrected_public_inputs;
-    for (const auto& index : constraint_system.public_inputs) {
-        corrected_public_inputs.emplace_back(index - pre_applied_noir_offset);
-    }
-
     // Construct a builder using the witness and public input data from acir
-    goblin_builder_ =
-        acir_format::GoblinBuilder{ goblin.op_queue, witness, corrected_public_inputs, constraint_system.varnum };
+    goblin_builder_ = acir_format::GoblinBuilder{
+        goblin.op_queue, witness, constraint_system.public_inputs, constraint_system.varnum
+    };
 
     // Populate constraints in the builder via the data in constraint_system
     acir_format::build_constraints(goblin_builder_, constraint_system, true);
diff --git a/barretenberg/cpp/src/barretenberg/proof_system/circuit_builder/goblin_ultra_circuit_builder.hpp b/barretenberg/cpp/src/barretenberg/proof_system/circuit_builder/goblin_ultra_circuit_builder.hpp
index 7fee2764e601..214d16dde80f 100644
--- a/barretenberg/cpp/src/barretenberg/proof_system/circuit_builder/goblin_ultra_circuit_builder.hpp
+++ b/barretenberg/cpp/src/barretenberg/proof_system/circuit_builder/goblin_ultra_circuit_builder.hpp
@@ -95,23 +95,9 @@ template <typename FF> class GoblinUltraCircuitBuilder_ : public UltraCircuitBui
                                auto& witness_values,
                                std::vector<uint32_t>& public_inputs,
                                size_t varnum)
-        : UltraCircuitBuilder_<arithmetization::UltraHonk<FF>>()
+        : UltraCircuitBuilder_<arithmetization::UltraHonk<FF>>(/*size_hint=*/0, witness_values, public_inputs, varnum)
         , op_queue(op_queue_in)
     {
-        // TODO(https://github.com/AztecProtocol/barretenberg/issues/816): NOTE: This still works even though the
-        // witness indices in the explicit acir gates are +1 offset because we're still adding the const 0 before
-        // anything else via the UCB constructor. Once we remove the +1 from Noir, we'll need to update the UCB by
-        // moving that const 0 to get these tests to pass again. Add the witness variables known directly from acir
-        for (size_t idx = 0; idx < varnum; ++idx) {
-            // Zeros are added for variables whose existence is known but whose values are not yet known. The values may
-            // be "set" later on via the assert_equal mechanism.
-            auto value = idx < witness_values.size() ? witness_values[idx] : 0;
-            this->add_variable(value);
-        }
-
-        // Add the public_inputs from acir
-        this->public_inputs = public_inputs;
-
         // Set indices to constants corresponding to Goblin ECC op codes
         set_goblin_ecc_op_code_constant_variables();
     };
diff --git a/barretenberg/cpp/src/barretenberg/proof_system/circuit_builder/ultra_circuit_builder.hpp b/barretenberg/cpp/src/barretenberg/proof_system/circuit_builder/ultra_circuit_builder.hpp
index 013410a2a4e5..63f65ed23d8b 100644
--- a/barretenberg/cpp/src/barretenberg/proof_system/circuit_builder/ultra_circuit_builder.hpp
+++ b/barretenberg/cpp/src/barretenberg/proof_system/circuit_builder/ultra_circuit_builder.hpp
@@ -682,12 +682,6 @@ class UltraCircuitBuilder_ : public CircuitBuilderBase<typename Arithmetization:
         w_o().reserve(size_hint);
         w_4().reserve(size_hint);
 
-        // TODO(https://github.com/AztecProtocol/barretenberg/issues/816): Once the hardcoded +1 offset is removed from
-        // noir, we'll need to move the addition of the const zero variable to after the acir witness has been
-        // incorporated into variables.
-        this->zero_idx = put_constant_variable(FF::zero());
-        this->tau.insert({ DUMMY_TAG, DUMMY_TAG }); // TODO(luke): explain this
-
         for (size_t idx = 0; idx < varnum; ++idx) {
             // Zeros are added for variables whose existence is known but whose values are not yet known. The values may
             // be "set" later on via the assert_equal mechanism.
@@ -697,6 +691,11 @@ class UltraCircuitBuilder_ : public CircuitBuilderBase<typename Arithmetization:
 
         // Add the public_inputs from acir
         this->public_inputs = public_inputs;
+
+        // Add the const zero variable after the acir witness has been
+        // incorporated into variables.
+        this->zero_idx = put_constant_variable(FF::zero());
+        this->tau.insert({ DUMMY_TAG, DUMMY_TAG }); // TODO(luke): explain this
     };
     UltraCircuitBuilder_(const UltraCircuitBuilder_& other) = default;
     UltraCircuitBuilder_(UltraCircuitBuilder_&& other)
diff --git a/noir/compiler/noirc_evaluator/src/ssa.rs b/noir/compiler/noirc_evaluator/src/ssa.rs
index deffe84baeab..f11c077d49a5 100644
--- a/noir/compiler/noirc_evaluator/src/ssa.rs
+++ b/noir/compiler/noirc_evaluator/src/ssa.rs
@@ -93,8 +93,8 @@ pub fn create_circuit(
     let mut generated_acir =
         optimize_into_acir(program, enable_ssa_logging, enable_brillig_logging)?;
     let opcodes = generated_acir.take_opcodes();
+    let current_witness_index = generated_acir.current_witness_index().0;
     let GeneratedAcir {
-        current_witness_index,
         return_witnesses,
         locations,
         input_witnesses,
diff --git a/noir/compiler/noirc_evaluator/src/ssa/acir_gen/acir_ir/generated_acir.rs b/noir/compiler/noirc_evaluator/src/ssa/acir_gen/acir_ir/generated_acir.rs
index 623810d1bfe8..73f30054cce8 100644
--- a/noir/compiler/noirc_evaluator/src/ssa/acir_gen/acir_ir/generated_acir.rs
+++ b/noir/compiler/noirc_evaluator/src/ssa/acir_gen/acir_ir/generated_acir.rs
@@ -28,9 +28,12 @@ use num_bigint::BigUint;
 /// The output of the Acir-gen pass
 pub(crate) struct GeneratedAcir {
     /// The next witness index that may be declared.
-    ///
+    /// If witness index is `None` then we have not yet created a witness
+    /// and thus next witness index that be declared is zero.
+    /// This field is private should only ever be accessed through its getter and setter.
+    /// 
     /// Equivalent to acvm::acir::circuit::Circuit's field of the same name.
-    pub(crate) current_witness_index: u32,
+    current_witness_index: Option<u32>,
 
     /// The opcodes of which the compiled ACIR will comprise.
     opcodes: Vec<AcirOpcode>,
@@ -60,7 +63,7 @@ pub(crate) struct GeneratedAcir {
 impl GeneratedAcir {
     /// Returns the current witness index.
     pub(crate) fn current_witness_index(&self) -> Witness {
-        Witness(self.current_witness_index)
+        Witness(self.current_witness_index.unwrap_or(0))
     }
 
     /// Adds a new opcode into ACIR.
@@ -78,8 +81,12 @@ impl GeneratedAcir {
     /// Updates the witness index counter and returns
     /// the next witness index.
     pub(crate) fn next_witness_index(&mut self) -> Witness {
-        self.current_witness_index += 1;
-        Witness(self.current_witness_index)
+        if let Some(current_index) = self.current_witness_index {
+            self.current_witness_index.replace(current_index + 1);
+        } else {
+            self.current_witness_index = Some(0);
+        }
+        Witness(self.current_witness_index.expect("ICE: current_witness_index should exist"))
     }
 
     /// Converts [`Expression`] `expr` into a [`Witness`].
diff --git a/noir/compiler/noirc_evaluator/src/ssa/acir_gen/mod.rs b/noir/compiler/noirc_evaluator/src/ssa/acir_gen/mod.rs
index e65e71b045d7..c0e3ed1ff661 100644
--- a/noir/compiler/noirc_evaluator/src/ssa/acir_gen/mod.rs
+++ b/noir/compiler/noirc_evaluator/src/ssa/acir_gen/mod.rs
@@ -294,7 +294,7 @@ impl Context {
         dfg: &DataFlowGraph,
     ) -> Result<Vec<Witness>, RuntimeError> {
         // The first witness (if any) is the next one
-        let start_witness = self.acir_context.current_witness_index().0 + 1;
+        let start_witness = self.acir_context.current_witness_index().0;
         for param_id in params {
             let typ = dfg.type_of_value(*param_id);
             let value = self.convert_ssa_block_param(&typ)?;
diff --git a/yarn-project/acir-simulator/src/client/client_execution_context.ts b/yarn-project/acir-simulator/src/client/client_execution_context.ts
index 5df69a7037e9..062cfdf4def7 100644
--- a/yarn-project/acir-simulator/src/client/client_execution_context.ts
+++ b/yarn-project/acir-simulator/src/client/client_execution_context.ts
@@ -106,7 +106,7 @@ export class ClientExecutionContext extends ViewDataOracle {
       ...args,
     ];
 
-    return toACVMWitness(1, fields);
+    return toACVMWitness(0, fields);
   }
 
   /**
diff --git a/yarn-project/acir-simulator/src/client/unconstrained_execution.ts b/yarn-project/acir-simulator/src/client/unconstrained_execution.ts
index d197ec386fbc..c59fe74c405e 100644
--- a/yarn-project/acir-simulator/src/client/unconstrained_execution.ts
+++ b/yarn-project/acir-simulator/src/client/unconstrained_execution.ts
@@ -26,7 +26,7 @@ export async function executeUnconstrainedFunction(
   log(`Executing unconstrained function ${contractAddress}:${functionSelector}`);
 
   const acir = Buffer.from(artifact.bytecode, 'base64');
-  const initialWitness = toACVMWitness(1, args);
+  const initialWitness = toACVMWitness(0, args);
   const { partialWitness } = await acvm(
     await AcirSimulator.getSolver(),
     acir,
diff --git a/yarn-project/acir-simulator/src/public/public_execution_context.ts b/yarn-project/acir-simulator/src/public/public_execution_context.ts
index 75942e7d93ca..886c0c40434b 100644
--- a/yarn-project/acir-simulator/src/public/public_execution_context.ts
+++ b/yarn-project/acir-simulator/src/public/public_execution_context.ts
@@ -53,7 +53,7 @@ export class PublicExecutionContext extends TypedOracle {
    * @param witnessStartIndex - The index where to start inserting the parameters.
    * @returns The initial witness.
    */
-  public getInitialWitness(witnessStartIndex = 1) {
+  public getInitialWitness(witnessStartIndex = 0) {
     const { callContext, args } = this.execution;
     const fields = [
       ...toACVMCallContext(callContext),