diff --git a/pulser-core/pulser/devices/_device_datacls.py b/pulser-core/pulser/devices/_device_datacls.py
index 61629040..9a1d44bd 100644
--- a/pulser-core/pulser/devices/_device_datacls.py
+++ b/pulser-core/pulser/devices/_device_datacls.py
@@ -684,19 +684,21 @@ def _specs(self, for_docs: bool = False) -> str:
                     (
                         "\t"
                         + r"- Maximum :math:`\Omega`:"
-                        + f" {ch.max_amp:.4g} rad/µs"
+                        + f" {float(cast(float,ch.max_amp)):.4g} rad/µs"
                     ),
                     (
                         (
                             "\t"
                             + r"- Maximum :math:`|\delta|`:"
-                            + f" {ch.max_abs_detuning:.4g} rad/µs"
+                            + f" {float(cast(float, ch.max_abs_detuning)):.4g}"
+                            + " rad/µs"
                         )
                         if not isinstance(ch, DMM)
                         else (
                             "\t"
                             + r"- Bottom :math:`|\delta|`:"
-                            + f" {ch.bottom_detuning:.4g} rad/µs"
+                            + f" {float(cast(float,ch.bottom_detuning)):.4g}"
+                            + " rad/µs"
                         )
                     ),
                     f"\t- Minimum average amplitude: {ch.min_avg_amp} rad/µs",
diff --git a/pulser-core/pulser/json/abstract_repr/deserializer.py b/pulser-core/pulser/json/abstract_repr/deserializer.py
index 0f16c6dd..d4bcfd2a 100644
--- a/pulser-core/pulser/json/abstract_repr/deserializer.py
+++ b/pulser-core/pulser/json/abstract_repr/deserializer.py
@@ -436,8 +436,18 @@ def convert_complex(obj: Any) -> Any:
 
     noise_types = noise_model_obj.pop("noise_types")
     with_leakage = "leakage" in noise_types
+    relevant_params = pulser.NoiseModel._find_relevant_params(
+        noise_types,
+        noise_model_obj["state_prep_error"],
+        noise_model_obj["amp_sigma"],
+        noise_model_obj["laser_waist"],
+    ) - {  # Handled separately
+        "eff_noise_rates",
+        "eff_noise_opers",
+        "with_leakage",
+    }
     noise_model = pulser.NoiseModel(
-        **noise_model_obj,
+        **{param: noise_model_obj[param] for param in relevant_params},
         eff_noise_rates=tuple(eff_noise_rates),
         eff_noise_opers=tuple(eff_noise_opers),
         with_leakage=with_leakage,
diff --git a/tests/test_abstract_repr.py b/tests/test_abstract_repr.py
index 4a69c0eb..7ef0bd12 100644
--- a/tests/test_abstract_repr.py
+++ b/tests/test_abstract_repr.py
@@ -49,7 +49,7 @@
 )
 from pulser.json.abstract_repr.validation import validate_abstract_repr
 from pulser.json.exceptions import AbstractReprError, DeserializeDeviceError
-from pulser.noise_model import NoiseModel
+from pulser.noise_model import _LEGACY_DEFAULTS, NoiseModel
 from pulser.parametrized.decorators import parametrize
 from pulser.parametrized.paramobj import ParamObj
 from pulser.parametrized.variable import Variable, VariableItem
@@ -194,7 +194,24 @@ def test_noise_model(noise_model: NoiseModel):
     re_noise_model = NoiseModel.from_abstract_repr(ser_noise_model_str)
     assert noise_model == re_noise_model
 
+    # Define parameters with defaults, like it was done before
+    # pulser-core < 0.20, and check deserialization still works
     ser_noise_model_obj = json.loads(ser_noise_model_str)
+    for param in ser_noise_model_obj:
+        if param in _LEGACY_DEFAULTS and (
+            # Case where only laser_waist is defined and adding non-zero
+            # amp_sigma adds requirement for "runs" and "samples_per_run"
+            param != "amp_sigma"
+            or "amplitude" not in noise_model.noise_types
+        ):
+            ser_noise_model_obj[param] = (
+                ser_noise_model_obj[param] or _LEGACY_DEFAULTS[param]
+            )
+    assert (
+        NoiseModel.from_abstract_repr(json.dumps(ser_noise_model_obj))
+        == re_noise_model
+    )
+
     with pytest.raises(TypeError, match="must be given as a string"):
         NoiseModel.from_abstract_repr(ser_noise_model_obj)