diff --git a/bfps/cpp/vorticity_equation.cpp b/bfps/cpp/vorticity_equation.cpp
index 47fb0c68907e441e9b49df7044755262b7f296be..def6b4a4549f2ced6ebfd453cd95c02d492580ee 100644
--- a/bfps/cpp/vorticity_equation.cpp
+++ b/bfps/cpp/vorticity_equation.cpp
@@ -302,7 +302,9 @@ void vorticity_equation<rnumber, be>::add_forcing(
     }
     if (strcmp(this->forcing_type, "Kolmogorov_and_drag") == 0)
     {
-        this->add_Kolmogorov_forcing(dst, this->fmode, this->famplitude);
+        double amplitude = this->famplitude * (
+                1 + this->friction_coefficient / sqrt(this->fmode  * this->famplitude));
+        this->add_Kolmogorov_forcing(dst, this->fmode, amplitude);
         this->add_field_band(
                 dst, vort_field,
                 0, this->fmode,