diff --git a/tfhe/src/core_crypto/algorithms/modulus_switch_noise_reduction.rs b/tfhe/src/core_crypto/algorithms/modulus_switch_noise_reduction.rs
index 1075ff18f6..402b404e9c 100644
--- a/tfhe/src/core_crypto/algorithms/modulus_switch_noise_reduction.rs
+++ b/tfhe/src/core_crypto/algorithms/modulus_switch_noise_reduction.rs
@@ -6,7 +6,7 @@ use crate::core_crypto::commons::traits::{Container, ContainerMut, UnsignedInteg
 use crate::core_crypto::entities::{LweCiphertext, LweCiphertextList};
 use crate::core_crypto::fft_impl::common::modulus_switch;
 use crate::core_crypto::prelude::{
-    CiphertextModulusLog, ContiguousEntityContainer, DispersionParameter,
+    CiphertextModulus, CiphertextModulusLog, ContiguousEntityContainer, DispersionParameter,
 };
 use itertools::Itertools;
 
@@ -128,6 +128,12 @@ where
         0,
         "Expected at least one encryption of zero"
     );
+    assert_eq!(
+        lwe.ciphertext_modulus(),
+        CiphertextModulus::new_native(),
+        "Non native modulus are not supported, got {}",
+        lwe.ciphertext_modulus(),
+    );
 
     let modulus = lwe.ciphertext_modulus().raw_modulus_float();
 
diff --git a/tfhe/src/core_crypto/algorithms/test/modulus_switch_noise_reduction.rs b/tfhe/src/core_crypto/algorithms/test/modulus_switch_noise_reduction.rs
index ecc9ae89eb..c71767800d 100644
--- a/tfhe/src/core_crypto/algorithms/test/modulus_switch_noise_reduction.rs
+++ b/tfhe/src/core_crypto/algorithms/test/modulus_switch_noise_reduction.rs
@@ -466,12 +466,14 @@ fn check_noise_improve_modulus_switch_noise(
         variance_improved / base_variance,
     );
 
+    let modulus = ciphertext_modulus.raw_modulus_float();
+
     let expected_base_variance = {
         let lwe_dim = lwe_dimension.0 as f64;
 
         let poly_size = 2_f64.powi((log_modulus.0 - 1) as i32);
 
-        (lwe_dim + 2.) * 2_f64.powi(128) / (96. * poly_size * poly_size) + (lwe_dim - 4.) / 48.
+        (lwe_dim + 2.) * modulus * modulus / (96. * poly_size * poly_size) + (lwe_dim - 4.) / 48.
     };
 
     assert!(
@@ -480,7 +482,7 @@ fn check_noise_improve_modulus_switch_noise(
     );
 
     let expected_variance_improved = Variance(expected_variance_improved.0 - input_variance.0)
-        .get_modular_variance(2_f64.powi(64))
+        .get_modular_variance(modulus)
         .value;
 
     assert!(