diff --git a/src/paper_thinstrip_mixed/tmixed_upscaledc.hh b/src/paper_thinstrip_mixed/tmixed_upscaledc.hh
index 83aa75a676b72c1e6b21af5ac3dfee6ed4aa85f6..bea9c727208e7948e46f74b911128d83e2453ced 100644
--- a/src/paper_thinstrip_mixed/tmixed_upscaledc.hh
+++ b/src/paper_thinstrip_mixed/tmixed_upscaledc.hh
@@ -78,8 +78,14 @@ template<typename Param, typename PAdaptor, typename CGFS, typename CContainer,
         auto phicOld = pAdapt.evalPhiCOld(xg);
         auto phiSolid = pAdapt.evalPhiSolid(xg);
         auto phiSolidOld = pAdapt.evalPhiSolidOld(xg);
+        RF source = 0;
+        if(xg > 0.1 && xg < 0.3)
+        {
+          source = (xg-0.1)*(0.3-xg);
+        }
         r.accumulate(lfsv,0, eg.geometry().volume()*
-          ((phic*c - phicOld*cOld + param.phys.uAst*(phiSolid-phiSolidOld))/param.time.dt));
+          ((phic*c - phicOld*cOld + param.phys.uAst*(phiSolid-phiSolidOld))/param.time.dt
+          + source));
         //std::cout << "bye alpha" << std::endl;
       } //alpha volume