diff --git a/opm/core/pressure/IncompTpfa.cpp b/opm/core/pressure/IncompTpfa.cpp
index a66ab4cbb..0b966e57b 100644
--- a/opm/core/pressure/IncompTpfa.cpp
+++ b/opm/core/pressure/IncompTpfa.cpp
@@ -109,7 +109,9 @@ namespace Opm
 	    }
 	}
 
-        const ifs_tpfa_forces F = { &src[0], bcs };
+        ifs_tpfa_forces F = { 0 };
+        if (! src.empty()) { F.src = &src[0]; }
+        F.bc = bcs;
 
 	ifs_tpfa_assemble(gg, &F, &trans_[0], &gpress_omegaweighted_[0], h_);