diff --git a/femwell/maxwell/waveguide.py b/femwell/maxwell/waveguide.py
index 3403f6be..4ffaebc5 100644
--- a/femwell/maxwell/waveguide.py
+++ b/femwell/maxwell/waveguide.py
@@ -329,7 +329,7 @@ def plot_component(
 
         if component == "x" or component == "y":
             plot_basis = mfield_t_basis.with_element(ElementVector(ElementDG(ElementTriP1())))
-            mfield_xy = plot_basis.project(mfield_t_basis.interpolate(conv_func(mfield_t)))
+            mfield_xy = plot_basis.project(conv_func(mfield_t_basis.interpolate(mfield_t)))
             (mfield_x, mfield_x_basis), (mfield_y, mfield_y_basis) = plot_basis.split(mfield_xy)
             if component == "x":
                 mfield_x_basis.plot(mfield_x, ax=ax, shading="gouraud")