diff --git a/packages/python/plotly/plotly/express/_imshow.py b/packages/python/plotly/plotly/express/_imshow.py
index c255bc32692..65a1f61da69 100644
--- a/packages/python/plotly/plotly/express/_imshow.py
+++ b/packages/python/plotly/plotly/express/_imshow.py
@@ -346,7 +346,7 @@ def imshow(
         binary_string = img.ndim >= (3 + slice_dimensions) and not is_dataframe
 
     # Cast bools to uint8 (also one byte)
-    if img.dtype == np.bool:
+    if img.dtype == np.bool_:
         img = 255 * img.astype(np.uint8)
 
     if range_color is not None: