diff --git a/src/nuspacesim/config.py b/src/nuspacesim/config.py
index 7b5faba..bd4174c 100644
--- a/src/nuspacesim/config.py
+++ b/src/nuspacesim/config.py
@@ -201,7 +201,7 @@ def log_nu_tau_energy(self) -> float:
     def nu_tau_energy(self) -> float:
         """10 ^ log_nu_tau_energy."""
         if isinstance(self.spectrum, MonoSpectrum):
-            return 10 ** self.nu_tau_energy()
+            return 10 ** self.log_nu_tau_energy
         else:
             return nan
 
diff --git a/test/core/test_config.py b/test/core/test_config.py
index 9e11505..11d4ba4 100644
--- a/test/core/test_config.py
+++ b/test/core/test_config.py
@@ -46,7 +46,7 @@ def test_detector_characteristics():
 def test_simulation_params():
     sp = nss.SimulationParameters()
     assert sp.N > 0
-    assert np.log10(sp.nu_tau_energy()) == sp.log_nu_tau_energy
+    assert np.log10(sp.nu_tau_energy) == sp.log_nu_tau_energy
     assert np.sin(sp.theta_ch_max) == sp.sin_theta_ch_max