diff --git a/opm/models/blackoil/blackoilintensivequantities.hh b/opm/models/blackoil/blackoilintensivequantities.hh
index bd745a15c..c1a50c0ff 100644
--- a/opm/models/blackoil/blackoilintensivequantities.hh
+++ b/opm/models/blackoil/blackoilintensivequantities.hh
@@ -96,8 +96,10 @@ class BlackOilIntensiveQuantities
     enum { dimWorld = GridView::dimensionworld };
     enum { compositionSwitchIdx = Indices::compositionSwitchIdx };
 
-    static const bool compositionSwitchEnabled = Indices::gasEnabled;
+    static const bool compositionSwitchEnabled = Indices::compositionSwitchIdx >= 0;
     static const bool waterEnabled = Indices::waterEnabled;
+    static const bool gasEnabled = Indices::gasEnabled;
+    static const bool oilEnabled = Indices::oilEnabled;
 
     using Toolbox = MathToolbox<Evaluation>;
     using DimMatrix = Dune::FieldMatrix<Scalar, dimWorld, dimWorld>;
@@ -167,6 +169,9 @@ public:
                 Sg = 0.0;
             }
         }
+        if (gasEnabled && waterEnabled && !oilEnabled) {
+            Sg = 1.0 - Sw; 
+        }
 
         Valgrind::CheckDefined(Sg);
         Valgrind::CheckDefined(Sw);