diff --git a/ebos/eclcpgridvanguard.hh b/ebos/eclcpgridvanguard.hh
index bc97a89ab..04d66c224 100644
--- a/ebos/eclcpgridvanguard.hh
+++ b/ebos/eclcpgridvanguard.hh
@@ -253,7 +253,8 @@ protected:
                                     /*isPeriodic=*/false,
                                     /*flipNormals=*/false,
                                     /*clipZ=*/false,
-                                    porv);
+                                    porv,
+                                    this->eclState().getInputNNC());
 
         // we use separate grid objects: one for the calculation of the initial condition
         // via EQUIL and one for the actual simulation. The reason is that the EQUIL code
diff --git a/ebos/ecltransmissibility.hh b/ebos/ecltransmissibility.hh
index f1a793593..f3d29f9ca 100644
--- a/ebos/ecltransmissibility.hh
+++ b/ebos/ecltransmissibility.hh
@@ -275,6 +275,14 @@ public:
                 unsigned insideFaceIdx  = intersection.indexInInside();
                 unsigned outsideFaceIdx = intersection.indexInOutside();
 
+                if (insideFaceIdx == -1) {
+                    // NNC. Set zero transmissibility, as it will be
+                    // *added to* by applyNncToGridTrans_() later.
+                    assert(outsideFaceIdx == -1);
+                    trans_[isId_(elemIdx, outsideElemIdx)] = 0.0;
+                    continue;
+                }
+
                 DimVector faceCenterInside;
                 DimVector faceCenterOutside;
                 DimVector faceAreaNormal;