diff --git a/interfaces/matlab/toolbox/@ThermoPhase/enthalpy_mole.m b/interfaces/matlab/toolbox/@ThermoPhase/enthalpy_mole.m
index f87bd1ddd..15e4b3baf 100644
--- a/interfaces/matlab/toolbox/@ThermoPhase/enthalpy_mole.m
+++ b/interfaces/matlab/toolbox/@ThermoPhase/enthalpy_mole.m
@@ -1,6 +1,6 @@
-function v = enthalpy_mole(a)
+function v = enthalpy_mole(tp)
 % ENTHALPY_MOLE  Get the mole specific enthalpy.
-% v = enthalpy_mole(a)
+% v = enthalpy_mole(tp)
 % :param tp:
 %     Instance of class :mat:func:`ThermoPhase` (or another
 %     object that derives from ThermoPhase)
@@ -8,4 +8,4 @@ function v = enthalpy_mole(a)
 %     Vector of molar specific enthalpies of the species. Units: J/kmol
 %
 
-v = thermo_get(a.tp_id, 2);
+v = thermo_get(tp.tp_id, 2);