diff --git a/srcF/sfx_z0m_all_surface.f90 b/srcF/sfx_z0m_all_surface.f90
index 8f2f11ec734ceec8b89fc30f261605cc99825448..b8455ed865b6abc360a4cda81eb8b3f22018b92d 100644
--- a/srcF/sfx_z0m_all_surface.f90
+++ b/srcF/sfx_z0m_all_surface.f90
@@ -29,7 +29,7 @@ module sfx_z0m_all_surface
 
     real, parameter :: h_charnock = 10.0
     real, parameter :: c1_charnock = log(h_charnock * (g / gamma_c))
-    real, parameter :: c2_charnock = Re_visc_min * nu_air * c1_charnock
+    real, parameter :: c2_charnock = Re_visc_min * nu_air * (g / gamma_c)
     real, parameter :: gamma_min = 0.01
     real, parameter :: gamma_max = 0.11
     real, parameter :: f_c = 100