diff --git a/Analysis/plot_eddy_contours.py b/Analysis/plot_eddy_contours.py
index ba680912ff8b14748898826154d40bad274cc87d..435fdfffe7c9f090927192715a428bb62c3e9571 100755
--- a/Analysis/plot_eddy_contours.py
+++ b/Analysis/plot_eddy_contours.py
@@ -325,6 +325,9 @@ if __name__ == "__main__":
         else:
             plt.show()
     else:
+        if not k1 <= args.anim[0] < args.anim[1] <= k1 + len(ishape_last) - 1:
+            sys.exit("Bad dates specified in option anim")
+            
         ani = make_animation(fig, ax, k1, ishape_last, readers,
                              window = args.window, k_min = args.anim[0],
                              k_max = args.anim[1], light = args.light)