diff --git a/plotly/shapeannotation.py b/plotly/shapeannotation.py
index a2323ed02d4..085b4fd8810 100644
--- a/plotly/shapeannotation.py
+++ b/plotly/shapeannotation.py
@@ -4,6 +4,9 @@
 def _mean(x):
     if len(x) == 0:
         raise ValueError("x must have positive length")
+
+    if len(x) == 2 and x[0] == x[1]:
+        return x[0]
     return float(sum(x)) / len(x)
 
 
diff --git a/tests/test_optional/test_autoshapes/test_annotated_shapes.py b/tests/test_optional/test_autoshapes/test_annotated_shapes.py
index 8d7c3806991..dfef857288b 100644
--- a/tests/test_optional/test_autoshapes/test_annotated_shapes.py
+++ b/tests/test_optional/test_autoshapes/test_annotated_shapes.py
@@ -52,6 +52,28 @@ def multi_plot_fixture():
     return fig
 
 
+from datetime import datetime, timedelta
+
+
+def test_add_shape_with_dates():
+    start_date = datetime(2025, 1, 1)
+    end_date = datetime(2025, 10, 10)
+    dates = []
+    current_date = start_date
+    while current_date <= end_date:
+        dates.append(current_date.strftime("%Y-%m-%d"))
+        current_date += timedelta(weeks=4)
+    print(dates)
+    fig = go.Figure(
+        data=[go.Scatter(x=[x for x in range(1, 20, 2)], y=dates)],
+        layout=go.Layout(
+            title=go.layout.Title(text="A Figure Specified By A Graph Object")
+        ),
+    )
+    fig.add_vline(x="2025-06-24", annotation_text="test")
+    assert len(fig.layout.annotations) == 1
+
+
 # Make sure adding a shape without specifying an annotation doesn't add any annotations
 def test_add_shape_no_annotation(multi_plot_fixture):
     multi_plot_fixture.add_hline(y=2, row="all", col="all")