diff --git a/resampler_notebook.ipynb b/resampler_notebook.ipynb
index 2f2a63e..c2167cd 100644
--- a/resampler_notebook.ipynb
+++ b/resampler_notebook.ipynb
@@ -9696,7 +9696,7 @@
     "      out[y, x] = image[y, x] * (num_levels - np.finfo(float).eps)\n",
     "      # Propagate the quantization residual.\n",
     "      residual = image[y, x] - out[y, x] / (num_levels - 1)\n",
-    "      for (dy, dx), weight in zip(offsets, weights):\n",
+    "      for (dy, dx), weight in zip(offsets, weights, strict=True):\n",
     "        yy, xx = y + dy, x + dx\n",
     "        if yy < height and 0 <= xx < width:\n",
     "          image[yy, xx] += residual * weight\n",
diff --git a/resampler_notebook.py b/resampler_notebook.py
index 66e97ee..da50539 100644
--- a/resampler_notebook.py
+++ b/resampler_notebook.py
@@ -4121,7 +4121,7 @@ def dither(
       out[y, x] = image[y, x] * (num_levels - np.finfo(float).eps)
       # Propagate the quantization residual.
       residual = image[y, x] - out[y, x] / (num_levels - 1)
-      for (dy, dx), weight in zip(offsets, weights):
+      for (dy, dx), weight in zip(offsets, weights, strict=True):
         yy, xx = y + dy, x + dx
         if yy < height and 0 <= xx < width:
           image[yy, xx] += residual * weight