diff --git a/MaterialLib/MPL/VariableType.cpp b/MaterialLib/MPL/VariableType.cpp
index 3a77a5f9fe08fee4ac117f715a9353cc203c012b..ebf1195616cc090067b40091d689e1bf58da644e 100644
--- a/MaterialLib/MPL/VariableType.cpp
+++ b/MaterialLib/MPL/VariableType.cpp
@@ -42,6 +42,10 @@ Variable convertStringToVariable(std::string const& input)
     {
         return Variable::temperature;
     }
+    if (boost::iequals(input, "molar_mass"))
+    {
+        return Variable::molar_mass;
+    }
     if (boost::iequals(input, "liquid_saturation"))
     {
         return Variable::liquid_saturation;
diff --git a/MaterialLib/MPL/VariableType.h b/MaterialLib/MPL/VariableType.h
index dcaca22adfcafac629a852577588db75a8bdb31b..68ba0534d4c8cb42a22aa39294483a6953b4cadc 100644
--- a/MaterialLib/MPL/VariableType.h
+++ b/MaterialLib/MPL/VariableType.h
@@ -53,6 +53,7 @@ enum class Variable : int
     grain_compressibility,
     liquid_saturation,
     mechanical_strain,
+    molar_mass,
     phase_pressure,
     porosity,
     solid_grain_pressure,