diff --git a/asp_plot/stereo.py b/asp_plot/stereo.py
index 49505e4..f3bc91c 100644
--- a/asp_plot/stereo.py
+++ b/asp_plot/stereo.py
@@ -282,7 +282,7 @@ def plot_dem_results(self, el_clim=None, ie_clim=None, diff_clim=None, save_dir=
             diff_clim = ColorBar(perc_range=(2, 98), symm=True).get_clim(diff)
 
         self.plot_array(ax=axa[2], array=diff, clim=diff_clim, cmap="RdBu", cbar_label="Elevation diff. (m)")
-        axa[2].set_title(f"Difference with reference DEM:\n{self.reference_dem.split("/")[-1]}")
+        axa[2].set_title(f"Difference with reference DEM:\n{self.reference_dem.split('/')[-1]}")
 
         fig.tight_layout()
         if save_dir and fig_fn: