diff --git a/src/Backends/Cubics/CubicBackend.h b/src/Backends/Cubics/CubicBackend.h
index 7144a158..3bc771eb 100644
--- a/src/Backends/Cubics/CubicBackend.h
+++ b/src/Backends/Cubics/CubicBackend.h
@@ -170,6 +170,11 @@ public:
         cubic.reset(new SRK(Tc, pc, acentric, R_u));
 	    setup();
     }
+    /// Update the state used to calculate the tangent-plane-distance
+    void update_TPD_state(){
+        AbstractCubic *cubic = get_cubic().get();
+        TPD_state.reset(new SRKBackend(cubic->get_Tc(),cubic->get_pc(),cubic->get_acentric(),cubic->get_R_u()));
+    };
 };
 
 class PengRobinsonBackend : public AbstractCubicBackend  {
@@ -200,6 +205,11 @@ public:
         cubic.reset(new PengRobinson(Tc, pc, acentric, R_u));
 	    setup();
     };
+    /// Update the state used to calculate the tangent-plane-distance
+    void update_TPD_state(){
+        AbstractCubic *cubic = get_cubic().get();
+        TPD_state.reset(new PengRobinsonBackend(cubic->get_Tc(),cubic->get_pc(),cubic->get_acentric(),cubic->get_R_u()));
+    };
 };
 
 /**
diff --git a/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.cpp b/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.cpp
index fd62f42e..c1384564 100644
--- a/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.cpp
+++ b/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.cpp
@@ -3301,10 +3301,7 @@ double HelmholtzEOSMixtureBackend::calc_tangent_plane_distance(const double T, c
 	if (w.size() != z.size()){ 
 		throw ValueError(format("Trial composition vector size [%d] is not the same as bulk composition [%d]", w.size(), z.size())); 
 	}
-	if (TPD_state.get() == NULL){
-		bool sat_states = false;
-		TPD_state.reset(new HelmholtzEOSMixtureBackend(components, sat_states));
-	}
+    update_TPD_state();
 	TPD_state->set_mole_fractions(std::vector<CoolPropDbl>(w.begin(), w.end()));
 	if (rhomolar_guess < 0){
 		TPD_state->update(PT_INPUTS, p, T);
diff --git a/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.h b/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.h
index cd9379ec..cd355ba2 100644
--- a/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.h
+++ b/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.h
@@ -23,6 +23,13 @@ protected:
     void pre_update(CoolProp::input_pairs &input_pair, CoolPropDbl &value1, CoolPropDbl &value2 );
     void post_update();
     shared_ptr<HelmholtzEOSMixtureBackend> TPD_state; ///< A temporary state used for calculations of the tangent-plane-distance
+    /// Update the state class used to calculate the tangent-plane-distance
+    virtual void update_TPD_state(){
+        if (TPD_state.get() == NULL){
+		    bool sat_states = false;
+		    TPD_state.reset(new HelmholtzEOSMixtureBackend(components, sat_states));
+	    }
+    };
     std::vector<CoolPropFluid> components; ///< The components that are in use
     phases imposed_phase_index;
     bool is_pure_or_pseudopure; ///< A flag for whether the substance is a pure or pseudo-pure fluid (true) or a mixture (false)
@@ -33,7 +40,6 @@ protected:
 
     SimpleState _crit;
     std::size_t N; ///< Number of components
-    
 public:
     HelmholtzEOSMixtureBackend();
     HelmholtzEOSMixtureBackend(const std::vector<CoolPropFluid> &components, bool generate_SatL_and_SatV = true);