diff --git a/halo2-ecc/src/bn254/tests/mod.rs b/halo2-ecc/src/bn254/tests/mod.rs
index c4ffb393..93c8a586 100644
--- a/halo2-ecc/src/bn254/tests/mod.rs
+++ b/halo2-ecc/src/bn254/tests/mod.rs
@@ -26,3 +26,4 @@ pub mod fixed_base_msm;
 pub mod msm;
 pub mod pairing;
 pub mod msm_sum_infinity;
+pub mod msm_sum_infinity_fixed_base;
diff --git a/halo2-ecc/src/bn254/tests/msm_sum_infinity_fixed_base.rs b/halo2-ecc/src/bn254/tests/msm_sum_infinity_fixed_base.rs
new file mode 100644
index 00000000..17405ed3
--- /dev/null
+++ b/halo2-ecc/src/bn254/tests/msm_sum_infinity_fixed_base.rs
@@ -0,0 +1,198 @@
+use crate::fields::FpStrategy;
+use ff::PrimeField;
+use halo2_base::gates::{
+    builder::{
+        CircuitBuilderStage, GateThreadBuilder, MultiPhaseThreadBreakPoints, RangeCircuitBuilder,
+    },
+    RangeChip,
+};
+use rand_core::OsRng;
+use std::fs::File;
+
+use super::*;
+
+#[derive(Clone, Copy, Debug, Serialize, Deserialize)]
+struct MSMCircuitParams {
+    strategy: FpStrategy,
+    degree: u32,
+    num_advice: usize,
+    num_lookup_advice: usize,
+    num_fixed: usize,
+    lookup_bits: usize,
+    limb_bits: usize,
+    num_limbs: usize,
+    batch_size: usize,
+    window_bits: usize,
+}
+
+fn msm_test(
+    builder: &mut GateThreadBuilder<Fr>,
+    params: MSMCircuitParams,
+    bases: Vec<G1Affine>,
+    scalars: Vec<Fr>,
+    window_bits: usize,
+) {
+    std::env::set_var("LOOKUP_BITS", params.lookup_bits.to_string());
+    let range = RangeChip::<Fr>::default(params.lookup_bits);
+    let fp_chip = FpChip::<Fr>::new(&range, params.limb_bits, params.num_limbs);
+    let ecc_chip = EccChip::new(&fp_chip);
+
+    let ctx = builder.main(0);
+    let scalars_assigned =
+        scalars.iter().map(|scalar| vec![ctx.load_witness(*scalar)]).collect::<Vec<_>>();
+    let bases_assigned = bases;
+        //.iter()
+        //.map(|base| ecc_chip.load_private_unchecked(ctx, (base.x, base.y)))
+        //.collect::<Vec<_>>();
+
+    let msm = ecc_chip.fixed_base_msm_in::<G1Affine>(
+        builder,
+        &bases_assigned,
+        scalars_assigned,
+        Fr::NUM_BITS as usize,
+        window_bits,
+        0,
+    );
+
+    let msm_answer = bases_assigned
+        .iter()
+        .zip(scalars.iter())
+        .map(|(base, scalar)| base * scalar)
+        .reduce(|a, b| a + b)
+        .unwrap()
+        .to_affine();
+
+    let msm_x = msm.x.value();
+    let msm_y = msm.y.value();
+    assert_eq!(msm_x, fe_to_biguint(&msm_answer.x));
+    assert_eq!(msm_y, fe_to_biguint(&msm_answer.y));
+}
+
+fn custom_msm_circuit(
+    params: MSMCircuitParams,
+    stage: CircuitBuilderStage,
+    break_points: Option<MultiPhaseThreadBreakPoints>,
+    bases: Vec<G1Affine>,
+    scalars: Vec<Fr>,
+) -> RangeCircuitBuilder<Fr> {
+    let k = params.degree as usize;
+    let mut builder = match stage {
+        CircuitBuilderStage::Mock => GateThreadBuilder::mock(),
+        CircuitBuilderStage::Prover => GateThreadBuilder::prover(),
+        CircuitBuilderStage::Keygen => GateThreadBuilder::keygen(),
+    };
+
+    let start0 = start_timer!(|| format!("Witness generation for circuit in {stage:?} stage"));
+    msm_test(&mut builder, params, bases, scalars, params.window_bits);
+
+    let circuit = match stage {
+        CircuitBuilderStage::Mock => {
+            builder.config(k, Some(20));
+            RangeCircuitBuilder::mock(builder)
+        }
+        CircuitBuilderStage::Keygen => {
+            builder.config(k, Some(20));
+            RangeCircuitBuilder::keygen(builder)
+        }
+        CircuitBuilderStage::Prover => RangeCircuitBuilder::prover(builder, break_points.unwrap()),
+    };
+    end_timer!(start0);
+    circuit
+}
+
+#[test]
+fn test_fb_msm1() {
+    let path = "configs/bn254/msm_circuit.config";
+    let mut params: MSMCircuitParams = serde_json::from_reader(
+        File::open(path).unwrap_or_else(|e| panic!("{path} does not exist: {e:?}")),
+    )
+    .unwrap();
+    params.batch_size = 3;
+
+    let random_point = G1Affine::random(OsRng);
+    let bases = vec![random_point, random_point, random_point];
+    let scalars = vec![Fr::one(), Fr::one(), -Fr::one() - Fr::one()];
+
+    let circuit = custom_msm_circuit(params, CircuitBuilderStage::Mock, None, bases, scalars);
+    MockProver::run(params.degree, &circuit, vec![]).unwrap().assert_satisfied();
+}
+
+#[test]
+fn test_fb_msm2() {
+    let path = "configs/bn254/msm_circuit.config";
+    let mut params: MSMCircuitParams = serde_json::from_reader(
+        File::open(path).unwrap_or_else(|e| panic!("{path} does not exist: {e:?}")),
+    )
+    .unwrap();
+    params.batch_size = 3;
+
+    let random_point = G1Affine::random(OsRng);
+    let bases = vec![random_point, random_point, (random_point + random_point).to_affine()];
+    let scalars = vec![Fr::one(), Fr::one(), -Fr::one()];
+
+    let circuit = custom_msm_circuit(params, CircuitBuilderStage::Mock, None, bases, scalars);
+    MockProver::run(params.degree, &circuit, vec![]).unwrap().assert_satisfied();
+}
+
+#[test]
+fn test_fb_msm3() {
+    let path = "configs/bn254/msm_circuit.config";
+    let mut params: MSMCircuitParams = serde_json::from_reader(
+        File::open(path).unwrap_or_else(|e| panic!("{path} does not exist: {e:?}")),
+    )
+    .unwrap();
+    params.batch_size = 4;
+
+    let random_point = G1Affine::random(OsRng);
+    let bases = vec![
+        random_point,
+        random_point,
+        random_point,
+        (random_point + random_point + random_point).to_affine(),
+    ];
+    let scalars = vec![Fr::one(), Fr::one(), Fr::one(), -Fr::one()];
+
+    let circuit = custom_msm_circuit(params, CircuitBuilderStage::Mock, None, bases, scalars);
+    MockProver::run(params.degree, &circuit, vec![]).unwrap().assert_satisfied();
+}
+
+#[test]
+fn test_fb_msm4() {
+    let path = "configs/bn254/msm_circuit.config";
+    let mut params: MSMCircuitParams = serde_json::from_reader(
+        File::open(path).unwrap_or_else(|e| panic!("{path} does not exist: {e:?}")),
+    )
+    .unwrap();
+    params.batch_size = 4;
+
+    let generator_point = G1Affine::generator();
+    let bases = vec![
+        generator_point,
+        generator_point,
+        generator_point,
+        (generator_point + generator_point + generator_point).to_affine(),
+    ];
+    let scalars = vec![Fr::one(), Fr::one(), Fr::one(), -Fr::one()];
+
+    let circuit = custom_msm_circuit(params, CircuitBuilderStage::Mock, None, bases, scalars);
+    MockProver::run(params.degree, &circuit, vec![]).unwrap().assert_satisfied();
+}
+
+#[test]
+fn test_fb_msm5() {
+    // Very similar example that does not add to infinity. It works fine.
+    let path = "configs/bn254/msm_circuit.config";
+    let mut params: MSMCircuitParams = serde_json::from_reader(
+        File::open(path).unwrap_or_else(|e| panic!("{path} does not exist: {e:?}")),
+    )
+    .unwrap();
+    params.batch_size = 4;
+
+    let random_point = G1Affine::random(OsRng);
+    let bases =
+        vec![random_point, random_point, random_point, (random_point + random_point).to_affine()];
+    let scalars = vec![-Fr::one(), -Fr::one(), Fr::one(), Fr::one()];
+
+    let circuit = custom_msm_circuit(params, CircuitBuilderStage::Mock, None, bases, scalars);
+    MockProver::run(params.degree, &circuit, vec![]).unwrap().assert_satisfied();
+}