diff --git a/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.cpp b/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.cpp
index 51768f8f..2a9ce891 100644
--- a/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.cpp
+++ b/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.cpp
@@ -1365,6 +1365,9 @@ void HelmholtzEOSMixtureBackend::T_phase_determination_pure_or_pseudopure(int ot
                 else if (value > p_liq){
                     this->_phase = iphase_liquid; _Q = 1000; return;
                 }
+                else if (!is_pure() && value < static_cast<long double>(_pLanc) && value > static_cast<long double>(_pVanc)){
+                    throw ValueError("Two-phase inputs not supported for pseudo-pure for now");
+                }
                 break;
             }
             default:
@@ -1432,8 +1435,7 @@ void HelmholtzEOSMixtureBackend::T_phase_determination_pure_or_pseudopure(int ot
             }
         }
 
-        // Determine Q based on the input provided
-        if (!is_pure_or_pseudopure){throw ValueError("possibly two-phase inputs not supported for pseudo-pure for now");}
+        
 
         // Actually have to use saturation information sadly
         // For the given temperature, find the saturation state
diff --git a/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.h b/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.h
index f3ebe5f7..e65df652 100644
--- a/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.h
+++ b/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.h
@@ -54,7 +54,7 @@ public:
     bool using_mole_fractions(){return true;}
     bool using_mass_fractions(){return false;}
     bool using_volu_fractions(){return false;}
-    bool is_pure(){ return is_pure_or_pseudopure; }
+    bool is_pure(){ return components.size() == 1 && !components[0]->EOSVector[0].pseudo_pure; }
     bool has_melting_line(){ return is_pure_or_pseudopure && components[0]->ancillaries.melting_line.enabled();};
     long double calc_melting_line(int param, int given, long double value);
     phases calc_phase(void){return _phase;};