diff --git a/dumux/assembly/cclocalassembler.hh b/dumux/assembly/cclocalassembler.hh
index 5d6f4072c0e7127d94dbd782f1ebcf7bdf254bc3..07ff71f0f3ee883cccee1e3f89bd408d03edce9e 100644
--- a/dumux/assembly/cclocalassembler.hh
+++ b/dumux/assembly/cclocalassembler.hh
@@ -428,7 +428,7 @@ private:
                 for (std::size_t k = 0; k < numNeighbors; ++k)
                     for (auto scvfIdx : connectivityMap[globalI][k].scvfsJ)
                     {
-                        neighborDeriv[k] += localResidual.evalFlux(problem,
+                        neighborDeriv[k] -= localResidual.evalFlux(problem,
                                                                    neighborElements[k],
                                                                    fvGeometry,
                                                                    curElemVolVars,