diff --git a/crates/specialized/rtx-fsi/tests/fsi2_harness/mod.rs b/crates/specialized/rtx-fsi/tests/fsi2_harness/mod.rs
index b88e7dc..0cca613 100644
--- a/crates/specialized/rtx-fsi/tests/fsi2_harness/mod.rs
+++ b/crates/specialized/rtx-fsi/tests/fsi2_harness/mod.rs
@@ -473,6 +473,7 @@ impl Fsi2Harness {
             },
             poisson_solver: PoissonSolverKind::Multigrid,
             poisson_precision: rtx_cfd::solvers::incompressible::MgPrecision::F64,
+            poisson_smoother: rtx_cfd::solvers::incompressible::MgSmoother::Lexicographic,
             // TVD, deliberately: FSI2 marches in time and needs the
             // shedding physics upwind's numerical viscosity killed on
             // these grids (CFD3's finding). The limiter chatter that