diff --git a/dumux/porousmediumflow/richardsextended/model.hh b/dumux/porousmediumflow/richardsextended/model.hh
index 25f756572b441a0bb9de0ca5b47729bce275d90f..6219de3c1b24e6faa1b8200f71aba712f4fa6e4d 100644
--- a/dumux/porousmediumflow/richardsextended/model.hh
+++ b/dumux/porousmediumflow/richardsextended/model.hh
@@ -18,7 +18,7 @@
  -
  \nabla \cdot \left\lbrace
  \varrho_w \frac{k_{rw}}{\mu_w} \; \mathbf{K} \;
- \left( \text{\nabla}
+ \left( \nabla
  p_w - \varrho_w \textbf{g}
  \right)
  +