diff --git a/km3buu/physics.py b/km3buu/physics.py
index fd295706204f582c0158d69f1cb23a76a6b89807..52954efbfda4dad6bb30299491bf571424973565 100644
--- a/km3buu/physics.py
+++ b/km3buu/physics.py
@@ -98,6 +98,7 @@ HE_PARAMS = {
     "Mkref": 2.698,
 }
 
+
 @np.vectorize
 def visible_energy_fraction(pdgid, energy):
     """
@@ -132,7 +133,7 @@ def visible_energy_fraction(pdgid, energy):
         weight = neutron_weight(tmp)
     elif pdgid == 2122:
         weight = proton_weight(tmp)
-    elif pdgid in [12,-12,14,-14,16,-16, -13, 13, 15, -15]:
+    elif pdgid in [12, -12, 14, -14, 16, -16, -13, 13, 15, -15]:
         weight = 0.0
     else:
         weight = proton_weight(tmp)