diff --git a/tensorflow_quantum/core/src/circuit_parser_qsim.cc b/tensorflow_quantum/core/src/circuit_parser_qsim.cc
index 2b3e81d19..3f180b426 100644
--- a/tensorflow_quantum/core/src/circuit_parser_qsim.cc
+++ b/tensorflow_quantum/core/src/circuit_parser_qsim.cc
@@ -182,8 +182,8 @@ inline Status TwoConstantGate(
     const unsigned int num_qubits, const unsigned int time,
     QsimCircuit* circuit, std::vector<GateMetaData>* metadata) {
   unsigned int q0, q1;
-  bool unused = absl::SimpleAtoi(op.qubits(0).id(), &q0);
-  unused = absl::SimpleAtoi(op.qubits(1).id(), &q1);
+  (void)absl::SimpleAtoi(op.qubits(0).id(), &q0);
+  (void)absl::SimpleAtoi(op.qubits(1).id(), &q1);
   auto gate = create_f(time, num_qubits - q0 - 1, num_qubits - q1 - 1);
   Status s = OptionalInsertControls(op, num_qubits, &gate);
   if (!s.ok()) {
@@ -208,10 +208,9 @@ inline Status SingleEigenGate(
     const unsigned int num_qubits, const unsigned int time,
     QsimCircuit* circuit, std::vector<GateMetaData>* metadata) {
   unsigned int q0;
-  bool unused;
   float exp, exp_s, gs;
   Status u;
-  unused = absl::SimpleAtoi(op.qubits(0).id(), &q0);
+  (void)absl::SimpleAtoi(op.qubits(0).id(), &q0);
 
   absl::optional<std::string> exponent_symbol;
   u = ParseProtoArg(op, "exponent", param_map, &exp, &exponent_symbol);
@@ -258,10 +257,9 @@ inline Status TwoEigenGate(
     QsimCircuit* circuit, std::vector<GateMetaData>* metadata) {
   unsigned int q0, q1;
   float exp, exp_s, gs;
-  bool unused;
   Status u;
-  unused = absl::SimpleAtoi(op.qubits(0).id(), &q0);
-  unused = absl::SimpleAtoi(op.qubits(1).id(), &q1);
+  (void)absl::SimpleAtoi(op.qubits(0).id(), &q0);
+  (void)absl::SimpleAtoi(op.qubits(1).id(), &q1);
 
   absl::optional<std::string> exponent_symbol;
   u = ParseProtoArg(op, "exponent", param_map, &exp, &exponent_symbol);
@@ -397,10 +395,9 @@ inline Status PhasedXGate(const Operation& op, const SymbolMap& param_map,
                           const unsigned int time, QsimCircuit* circuit,
                           std::vector<GateMetaData>* metadata) {
   int q0;
-  bool unused;
   float pexp, pexp_s, exp, exp_s, gs;
   Status u;
-  unused = absl::SimpleAtoi(op.qubits(0).id(), &q0);
+  (void)absl::SimpleAtoi(op.qubits(0).id(), &q0);
 
   absl::optional<std::string> exponent_symbol;
   u = ParseProtoArg(op, "exponent", param_map, &exp, &exponent_symbol);
@@ -457,11 +454,10 @@ inline Status FsimGate(const Operation& op, const SymbolMap& param_map,
                        QsimCircuit* circuit,
                        std::vector<GateMetaData>* metadata) {
   int q0, q1;
-  bool unused;
   float theta, theta_s, phi, phi_s;
   Status u;
-  unused = absl::SimpleAtoi(op.qubits(0).id(), &q0);
-  unused = absl::SimpleAtoi(op.qubits(1).id(), &q1);
+  (void)absl::SimpleAtoi(op.qubits(0).id(), &q0);
+  (void)absl::SimpleAtoi(op.qubits(1).id(), &q1);
 
   absl::optional<std::string> theta_symbol;
   u = ParseProtoArg(op, "theta", param_map, &theta, &theta_symbol);
@@ -514,11 +510,10 @@ inline Status PhasedISwapGate(const Operation& op, const SymbolMap& param_map,
                               const unsigned int time, QsimCircuit* circuit,
                               std::vector<GateMetaData>* metadata) {
   int q0, q1;
-  bool unused;
   float pexp, pexp_s, exp, exp_s;
   Status u;
-  unused = absl::SimpleAtoi(op.qubits(0).id(), &q0);
-  unused = absl::SimpleAtoi(op.qubits(1).id(), &q1);
+  (void)absl::SimpleAtoi(op.qubits(0).id(), &q0);
+  (void)absl::SimpleAtoi(op.qubits(1).id(), &q1);
 
   absl::optional<std::string> exponent_symbol;
   u = ParseProtoArg(op, "exponent", param_map, &exp, &exponent_symbol);
@@ -605,10 +600,9 @@ inline Status AsymmetricDepolarizingChannel(const Operation& op,
                                             const unsigned int time,
                                             NoisyQsimCircuit* ncircuit) {
   int q;
-  bool unused;
   float p_x, p_y, p_z;
   Status u;
-  unused = absl::SimpleAtoi(op.qubits(0).id(), &q);
+  (void)absl::SimpleAtoi(op.qubits(0).id(), &q);
 
   u = ParseProtoArg(op, "p_x", {}, &p_x);
   u = ParseProtoArg(op, "p_y", {}, &p_y);
@@ -627,10 +621,9 @@ inline Status DepolarizingChannel(const Operation& op,
                                   const unsigned int time,
                                   NoisyQsimCircuit* ncircuit) {
   int q;
-  bool unused;
   float p;
   Status u;
-  unused = absl::SimpleAtoi(op.qubits(0).id(), &q);
+  (void)absl::SimpleAtoi(op.qubits(0).id(), &q);
 
   u = ParseProtoArg(op, "p", {}, &p);
   if (!u.ok()) {
@@ -645,10 +638,9 @@ inline Status DepolarizingChannel(const Operation& op,
 inline Status GADChannel(const Operation& op, const unsigned int num_qubits,
                          const unsigned int time, NoisyQsimCircuit* ncircuit) {
   int q;
-  bool unused;
   float p, gamma;
   Status u;
-  unused = absl::SimpleAtoi(op.qubits(0).id(), &q);
+  (void)absl::SimpleAtoi(op.qubits(0).id(), &q);
 
   u = ParseProtoArg(op, "p", {}, &p);
   if (!u.ok()) {
@@ -669,8 +661,7 @@ inline Status ResetChannel(const Operation& op, const unsigned int num_qubits,
                            const unsigned int time,
                            NoisyQsimCircuit* ncircuit) {
   int q;
-  bool unused;
-  unused = absl::SimpleAtoi(op.qubits(0).id(), &q);
+  (void)absl::SimpleAtoi(op.qubits(0).id(), &q);
 
   auto chan = qsim::Cirq::ResetChannel<float>::Create(time, num_qubits - q - 1);
   ncircuit->channels.push_back(chan);
@@ -682,10 +673,9 @@ inline Status AmplitudeDampingChannel(const Operation& op,
                                       const unsigned int time,
                                       NoisyQsimCircuit* ncircuit) {
   int q;
-  bool unused;
   float gamma;
   Status u;
-  unused = absl::SimpleAtoi(op.qubits(0).id(), &q);
+  (void)absl::SimpleAtoi(op.qubits(0).id(), &q);
 
   u = ParseProtoArg(op, "gamma", {}, &gamma);
   if (!u.ok()) {
@@ -702,10 +692,9 @@ inline Status PhaseDampingChannel(const Operation& op,
                                   const unsigned int time,
                                   NoisyQsimCircuit* ncircuit) {
   int q;
-  bool unused;
   float gamma;
   Status u;
-  unused = absl::SimpleAtoi(op.qubits(0).id(), &q);
+  (void)absl::SimpleAtoi(op.qubits(0).id(), &q);
 
   u = ParseProtoArg(op, "gamma", {}, &gamma);
   if (!u.ok()) {
@@ -723,10 +712,9 @@ inline Status PhaseFlipChannel(const Operation& op,
                                const unsigned int time,
                                NoisyQsimCircuit* ncircuit) {
   int q;
-  bool unused;
   float p;
   Status u;
-  unused = absl::SimpleAtoi(op.qubits(0).id(), &q);
+  (void)absl::SimpleAtoi(op.qubits(0).id(), &q);
 
   u = ParseProtoArg(op, "p", {}, &p);
   if (!u.ok()) {
@@ -743,10 +731,9 @@ inline Status BitFlipChannel(const Operation& op, const unsigned int num_qubits,
                              const unsigned int time,
                              NoisyQsimCircuit* ncircuit) {
   int q;
-  bool unused;
   float p;
   Status u;
-  unused = absl::SimpleAtoi(op.qubits(0).id(), &q);
+  (void)absl::SimpleAtoi(op.qubits(0).id(), &q);
 
   u = ParseProtoArg(op, "p", {}, &p);
   if (!u.ok()) {
diff --git a/tensorflow_quantum/core/src/circuit_parser_qsim_test.cc b/tensorflow_quantum/core/src/circuit_parser_qsim_test.cc
index bdecfe804..f5add3c8a 100644
--- a/tensorflow_quantum/core/src/circuit_parser_qsim_test.cc
+++ b/tensorflow_quantum/core/src/circuit_parser_qsim_test.cc
@@ -64,7 +64,7 @@ Arg MakeControlArg(const std::string& val) {
 }
 
 inline void AssertControlEqual(const QsimGate& a, const QsimGate& b) {
-  for (size_t i = 0; i < a.controlled_by.size(); i++) {
+  for (unsigned int i = 0; i < a.controlled_by.size(); i++) {
     ASSERT_EQ(a.controlled_by[i], b.controlled_by[i]);
   }
   ASSERT_EQ(a.cmask, b.cmask);
@@ -89,7 +89,7 @@ inline void AssertOneQubitEqual(const QsimGate& a, const QsimGate& b) {
 
 inline void AssertChannelEqual(const QsimChannel& a, const QsimChannel& b) {
   ASSERT_EQ(a.size(), b.size());
-  for (size_t i = 0; i < a.size(); i++) {
+  for (unsigned int i = 0; i < a.size(); i++) {
     ASSERT_EQ(a[i].kind, b[i].kind);
     ASSERT_EQ(a[i].unitary, b[i].unitary);
     ASSERT_NEAR(a[i].prob, b[i].prob, 1e-5);