diff --git a/dpm_tools/visualization/_plot_3d.py b/dpm_tools/visualization/_plot_3d.py
index 80792a5..5e26efc 100644
--- a/dpm_tools/visualization/_plot_3d.py
+++ b/dpm_tools/visualization/_plot_3d.py
@@ -170,8 +170,8 @@ def plot_isosurface(data, fig: pv.Plotter = None, show_isosurface: list = None,
     if show_isosurface is None:
         show_isosurface = [(np.amax(data.scalar) + np.amin(data.scalar)) / 2]
         warnings.warn("\n\nNo value provided for \'show_isosurfaces\' keyword. " +
-                      f"Using the midpoint of the isosurface array instead ({np.amin(data.scalar)},{
-                          np.amax(data.scalar)}).\n",
+                      f"Using the midpoint of the isosurface array instead ({np.amin(data.scalar)},\
+                      {np.amax(data.scalar)}).\n",
                       stacklevel=2)
 
     contours = pv_image_obj.contour(isosurfaces=show_isosurface)