diff --git a/src/general/semidiscretization.jl b/src/general/semidiscretization.jl
index ad4333e47..d1eb43cab 100644
--- a/src/general/semidiscretization.jl
+++ b/src/general/semidiscretization.jl
@@ -117,11 +117,17 @@ end
     return compact_support(system, system.boundary_model, neighbor)
 end
 
-@inline function compact_support(system, model, neighbor)
+@inline function compact_support(system, model::BoundaryModelMonaghanKajtar, neighbor)
     # Use the compact support of the fluid for solid-fluid interaction
     return compact_support(neighbor, system)
 end
 
+@inline function compact_support(system, model::BoundaryModelMonaghanKajtar,
+                                 neighbor::BoundarySPHSystem)
+    # This NHS is never used
+    return 0.0
+end
+
 @inline function compact_support(system, model::BoundaryModelDummyParticles, neighbor)
     # TODO: Monaghan-Kajtar BC are using the fluid's compact support for solid-fluid
     # interaction. Dummy particle BC use the model's compact support, which is also used