diff --git a/cosipy/modules/albedo.py b/cosipy/modules/albedo.py
index 2e6afd3e..2767f73a 100644
--- a/cosipy/modules/albedo.py
+++ b/cosipy/modules/albedo.py
@@ -242,9 +242,8 @@ def method_Bougamont(GRID, surface_temperature: float, albedo_snow: float):
         temperature-dependant decay timescales."""
 
         # slightly faster than one-liner
-        t_star_days = float(t_star) * float(dt_days)
         delta_albedo = albedo_snow - albedo_firn
-        albedo_snow -= delta_albedo / t_star_days
+        albedo_snow -= delta_albedo * float(dt_days) / float(t_star)
 
         # Reset if snowfall in current timestep
         if hours_since_snowfall == 0:
diff --git a/cosipy/tests/test_parameterisation_albedo.py b/cosipy/tests/test_parameterisation_albedo.py
index 89755767..489e0393 100644
--- a/cosipy/tests/test_parameterisation_albedo.py
+++ b/cosipy/tests/test_parameterisation_albedo.py
@@ -107,8 +107,11 @@ def test_updateAlbedo_method(
             surface_temperature=270.0,
             albedo_snow=Constants.albedo_fresh_snow,
         )
-        assert isinstance(surface_albedo, float)
-        assert isinstance(snow_albedo, float)
+        for albedo in [surface_albedo, snow_albedo]:
+            assert isinstance(albedo, float)
+            assert 0.0 <= albedo <= 1.0
+        
+        
 
     @pytest.mark.parametrize("arg_method", ["Wrong Method", "", None])
     def test_updateAlbedo_method_error(