diff --git a/opm/core/props/BlackoilPropertiesFromDeck.cpp b/opm/core/props/BlackoilPropertiesFromDeck.cpp
index 0795d3f27..97d0a6e65 100644
--- a/opm/core/props/BlackoilPropertiesFromDeck.cpp
+++ b/opm/core/props/BlackoilPropertiesFromDeck.cpp
@@ -322,8 +322,8 @@ namespace Opm
             this->compute_R_(n, p, T, z, cells, &R_[0]);
         }
         const auto& pu = phaseUsage();
-        bool oil_and_gas = pu.phase_pos[BlackoilPhases::Liquid] &&
-            pu.phase_pos[BlackoilPhases::Vapour];
+        bool oil_and_gas = pu.phase_used[BlackoilPhases::Liquid] &&
+            pu.phase_used[BlackoilPhases::Vapour];
         const int o = pu.phase_pos[BlackoilPhases::Liquid];
         const int g = pu.phase_pos[BlackoilPhases::Vapour];
 
diff --git a/opm/core/props/phaseUsageFromDeck.hpp b/opm/core/props/phaseUsageFromDeck.hpp
index c7890ebd3..88571e452 100644
--- a/opm/core/props/phaseUsageFromDeck.hpp
+++ b/opm/core/props/phaseUsageFromDeck.hpp
@@ -94,7 +94,7 @@ namespace Opm
             }
             else {
                 //Set to ridiculous value on purpose: should never be used
-                pu.phase_pos[i] = -1;
+                pu.phase_pos[i] = 2000000000;
             }
         }