diff --git a/tupak/gw/prior.py b/tupak/gw/prior.py
index 7a0360511bac5f89baee6921b21b43bfdcfb4a02..f96b4b612105a02a049a5194eef32c69a5a6e02b 100644
--- a/tupak/gw/prior.py
+++ b/tupak/gw/prior.py
@@ -138,8 +138,8 @@ Prior._default_latex_labels = {
     'psi': '$\psi$',
     'phase': '$\phi$',
     'geocent_time': '$t_c$',
-    'lambda1' : '$\\Lambda_1$',
-    'lambda2' : '$\\Lambda_2$'}
+    'lambda_1': '$\\Lambda_1$',
+    'lambda_2': '$\\Lambda_2$'}
 
 
 class CalibrationPriorSet(PriorSet):
diff --git a/tupak/gw/prior_files/binary_neutron_stars.prior b/tupak/gw/prior_files/binary_neutron_stars.prior
index f2195140e8aa6fefd7340d7d766104d7690b05fd..693b021a9362b305d604f5bbee602c5655e4b428 100644
--- a/tupak/gw/prior_files/binary_neutron_stars.prior
+++ b/tupak/gw/prior_files/binary_neutron_stars.prior
@@ -17,5 +17,5 @@ iota =  Sine(name='iota')
 # cos_iota =  Uniform(name='cos_iota', minimum=-1, maximum=1)
 psi =  Uniform(name='psi', minimum=0, maximum=np.pi)
 phase =  Uniform(name='phase', minimum=0, maximum=2 * np.pi)
-lambda1 = tupak.prior.Uniform(name='lambda1', minimum=0, maximum=3000 )
-lambda2 = tupak.prior.Uniform(name='lambda2', minimum=0, maximum=3000 )
+lambda_1 = tupak.prior.Uniform(name='lambda_1', minimum=0, maximum=3000 )
+lambda_2 = tupak.prior.Uniform(name='lambda_2', minimum=0, maximum=3000 )
diff --git a/tupak/gw/source.py b/tupak/gw/source.py
index cb27e4e5a9c4163fe116b6011598bf62ad8f539f..9dcc9924e066d11051ea53183bfdef98f511d4a9 100644
--- a/tupak/gw/source.py
+++ b/tupak/gw/source.py
@@ -255,7 +255,7 @@ def supernova_pca_model(
 
 def lal_binary_neutron_star(
         frequency_array, mass_1, mass_2, luminosity_distance, a_1, a_2,
-        iota, phase, ra, dec, geocent_time, psi, lambda1, lambda2, **kwargs):
+        iota, phase, lambda_1, lambda_2, ra, dec, geocent_time, psi, **kwargs):
     """ A Binary Neutron Star waveform model using lalsimulation
 
     Parameters
@@ -284,9 +284,9 @@ def lal_binary_neutron_star(
         The time at coalescence
     psi: float
         Orbital polarisation
-    lambda1: float
+    lambda_1: float
         Dimensionless tidal deformability of mass_1
-    lambda2: float
+    lambda_2: float
         Dimensionless tidal deformability of mass_2
         
     kwargs: dict
@@ -323,8 +323,8 @@ def lal_binary_neutron_star(
     mean_per_ano = 0.0
     
     waveform_dictionary = lal.CreateDict()
-    lalsim.SimInspiralWaveformParamsInsertTidalLambda1(waveform_dictionary, lambda1)
-    lalsim.SimInspiralWaveformParamsInsertTidalLambda2(waveform_dictionary, lambda2)
+    lalsim.SimInspiralWaveformParamsInsertTidalLambda1(waveform_dictionary, lambda_1)
+    lalsim.SimInspiralWaveformParamsInsertTidalLambda2(waveform_dictionary, lambda_2)
 
     approximant = lalsim.GetApproximantFromString(waveform_approximant)