diff --git a/kf_book/book_plots.py b/kf_book/book_plots.py
index 8b61b8c..743f4b3 100644
--- a/kf_book/book_plots.py
+++ b/kf_book/book_plots.py
@@ -535,10 +535,10 @@ def plot_filter(xs, ys=None, c='#013afe', label='Filter', var=None, **kwargs):
         ys = xs
         xs = range(len(ys))
 
-    plt.plot(xs, ys, color=c, label=label, **kwargs)
+    retval = plt.plot(xs, ys, color=c, label=label, **kwargs)
 
     if var is None:
-        return
+        return retval
 
     var = np.asarray(var)
 
@@ -551,6 +551,8 @@ def plot_filter(xs, ys=None, c='#013afe', label='Filter', var=None, **kwargs):
     plt.fill_between(xs, std_btm, std_top,
                      facecolor='yellow', alpha=0.2)
 
+    return retval
+
 
 
 
diff --git a/kf_book/gh_internal.py b/kf_book/gh_internal.py
index b57c6ed..968755f 100644
--- a/kf_book/gh_internal.py
+++ b/kf_book/gh_internal.py
@@ -54,13 +54,13 @@ def plot_gh_results(weights, estimates, predictions, time_step=0):
         plt.gcf().canvas.draw()
         time.sleep(time_step)
 
-        book_plots.plot_filter(xs[:i+1], estimates[:i+1], marker='o')
+        est, = book_plots.plot_filter(xs[:i+1], estimates[:i+1], marker='o')
         plt.xlim([-1, n+1])
         plt.ylim([156.0, 173])
         plt.gcf().canvas.draw()
         time.sleep(time_step)
 
-        plt.legend([act, scale, pred], ['Actual Weight', 'Measurement', 'Predictions'], loc=4)
+        plt.legend([act, scale, est, pred], ['Actual Weight', 'Measurement', 'Estimates', 'Predictions'], loc=4)
     book_plots.set_labels(x='day', y='weight (lbs)')