diff --git a/src/assemblers.cc b/src/assemblers.cc
index d3cff5ccdd69bdfe232834e04fa455f7058f417d..7194effe5cd4ea094d00592a6e7fa0cff3c8b0a1 100644
--- a/src/assemblers.cc
+++ b/src/assemblers.cc
@@ -90,6 +90,8 @@ assemble_nonlinearity(
           nodalIntegrals, a, mu, eta, normalStress, b, state, L, h);
     }
     case Config::Laursen:
+      assert(false); // Known to be broken
+
       // TODO: take state and h into account
       // FIXME: We should be using a quadratic rather than a linear function
       // here!