diff --git a/cpp/kspace.cpp b/cpp/kspace.cpp
index 08f991edd55ec83a2a994b09846785404c1941f0..1549b2dad869207cbf4482246e92823f64542c09 100644
--- a/cpp/kspace.cpp
+++ b/cpp/kspace.cpp
@@ -361,7 +361,7 @@ void kspace<be, dt>::general_M_filter(
                     for (unsigned int tcounter=0; tcounter<2*ncomp(fc); tcounter++)
                         ((rnumber*)a)[2*ncomp(fc)*cindex + tcounter] *= (
 //                            prefactor * (std::exp(-0.5*std::pow((2.9*argument),(68.0*(std::pow(ell,0.74))))) * std::sqrt(1.0 + (std::pow((argument/0.06),3.8))/(1.0 + (std::pow((argument/0.057),3.8))))));
-                            prefactor * (std::exp(-1.7*argument)) * std::sqrt(1.0 + 0.68*(std::pow((argument/0.065),4.6))/(1.0 + (std::pow((argument/0.065),4.6)))));
+                            prefactor * (std::exp(-1.9392478*std::pow(argument,0.66231261))) * std::sqrt(1.0 + 2.48991336*(std::pow((argument/0.07444272),2.27175433))/(1.0 + (std::pow((argument/0.07444272),2.27175433)))));
                 }
                 });
 }