diff --git a/opm/material/fluidstates/BlackOilFluidState.hpp b/opm/material/fluidstates/BlackOilFluidState.hpp
index e85f36bc0..c8ff10320 100644
--- a/opm/material/fluidstates/BlackOilFluidState.hpp
+++ b/opm/material/fluidstates/BlackOilFluidState.hpp
@@ -79,14 +79,14 @@ LhsEval getInvB_(typename std::enable_if<!HasMember_invB<FluidState>::value,
 OPM_GENERATE_HAS_MEMBER(saltConcentration, ) // Creates 'HasMember_saltConcentration<T>'.
 
 template <class FluidState>
-unsigned getSaltConcentration_(typename std::enable_if<HasMember_saltConcentration<FluidState>::value,
+auto getSaltConcentration_(typename std::enable_if<HasMember_saltConcentration<FluidState>::value,
                                                     const FluidState&>::type fluidState)
 { return fluidState.saltConcentration(); }
 
 template <class FluidState>
-unsigned getSaltConcentration_(typename std::enable_if<!HasMember_saltConcentration<FluidState>::value,
+auto getSaltConcentration_(typename std::enable_if<!HasMember_saltConcentration<FluidState>::value,
                                                     const FluidState&>::type fluidState OPM_UNUSED)
-{ return 0; }
+{ return 0.0; }
 
 /*!
  * \brief Implements a "tailor-made" fluid state class for the black-oil model.