diff --git a/examples/compressible/mountain_hydrostatic.py b/examples/compressible/mountain_hydrostatic.py
index 98d221db6..2fe88206d 100644
--- a/examples/compressible/mountain_hydrostatic.py
+++ b/examples/compressible/mountain_hydrostatic.py
@@ -56,7 +56,7 @@
 
 # Equation
 parameters = CompressibleParameters(g=9.80665, cp=1004.)
-sponge = SpongeLayerParameters(H=H, z_level=H-20000, mubar=0.3/dt)
+sponge = SpongeLayerParameters(H=H, z_level=H-20000, mubar=0.3)
 eqns = CompressibleEulerEquations(domain, parameters, sponge=sponge)
 
 # I/O