diff --git a/opm/core/pressure/CompressibleTpfa.cpp b/opm/core/pressure/CompressibleTpfa.cpp
index cc15f7f5..f6e0db1a 100644
--- a/opm/core/pressure/CompressibleTpfa.cpp
+++ b/opm/core/pressure/CompressibleTpfa.cpp
@@ -458,6 +458,7 @@ namespace Opm
         forces.wells = &wells_tmp;
         forces.src = NULL; // Check if it is legal to leave it as NULL.
         compr_quantities_gen cq;
+        cq.nphases = props_.numPhases();
         cq.Ac = &cell_A_[0];
         cq.dAc = &cell_dA_[0];
         cq.Af = &face_A_[0];