diff --git a/development/support/segment_tehmina_em_data.py b/development/support/segment_tehmina_em_data.py
new file mode 100644
index 000000000..c53b6d583
--- /dev/null
+++ b/development/support/segment_tehmina_em_data.py
@@ -0,0 +1,79 @@
+import numpy as np
+from tqdm import tqdm
+import imageio.v3 as imageio
+
+from bioimage_cpp.transformation import resample
+
+from micro_sam.automatic_segmentation import get_predictor_and_segmenter
+
+
+IMAGE_PATH = "/home/anwai/data/tehmina_data/Anwai/image_1066422_z900.tif"
+CHECKPOINT_PATH = "/home/anwai/data/tehmina_data/Anwai/downsample/best.pt"
+OUTPUT_PATH = "/home/anwai/data/tehmina_data/Anwai/image_1066422_z900_prediction.tif"
+
+# The model was finetuned on images downsampled by 2, e.g. (7813, 6823) -> (3906, 3411).
+DOWNSCALE_FACTOR = 2
+# Tile plus halo on both sides is 1024, the finetuning patch shape.
+TILE_SHAPE, HALO = (512, 512), (256, 256)
+STATE_KEYS = ("foreground", "center_distances", "boundary_distances")
+
+
+def resize(data, shape, order):
+    # Same pixel center mapping as skimage.transform.resize.
+    scales = np.array(data.shape) / np.array(shape)
+    matrix = np.concatenate([np.diag(scales), (0.5 * scales - 0.5)[:, None]], axis=1)
+    return resample(data, matrix, bounding_box=tuple(slice(0, s) for s in shape), order=order)
+
+
+def feather_weights(shape):
+    # Linear ramps over the overlap of neighboring tiles, which is two times the halo.
+    profiles = []
+    for size, halo in zip(shape, HALO):
+        distance = np.minimum(np.arange(size), np.arange(size)[::-1]) + 0.5
+        profiles.append(np.minimum(distance / (2 * halo), 1))
+    return np.outer(*profiles)
+
+
+def get_tiles(shape):
+    (ty, tx), (hy, hx) = TILE_SHAPE, HALO
+    return [
+        (slice(max(y - hy, 0), min(y + ty + hy, shape[0])), slice(max(x - hx, 0), min(x + tx + hx, shape[1])))
+        for y in range(0, shape[0], ty) for x in range(0, shape[1], tx)
+    ]
+
+
+def segment(image):
+    image = image.astype(np.float32)
+    image = 255 * (image - image.min()) / (image.max() - image.min() + 1e-8)
+    _, segmenter = get_predictor_and_segmenter(model_type="vit_b", checkpoint=CHECKPOINT_PATH, segmentation_mode="ais")
+
+    # Feathered stitching: average overlapping tile outputs to avoid cuts at the tile borders.
+    maps, weight_sum = np.zeros((3,) + image.shape, dtype="float32"), np.zeros(image.shape, dtype="float32")
+    for tile in tqdm(get_tiles(image.shape), desc="Predict tiles"):
+        segmenter.initialize(image[tile])
+        state = segmenter.get_state()
+        weights = feather_weights(image[tile].shape)
+        maps[(slice(None),) + tile] += weights * np.stack([state[key] for key in STATE_KEYS])
+        weight_sum[tile] += weights
+
+    segmenter.set_state(dict(zip(STATE_KEYS, maps / weight_sum)))
+    return segmenter.generate()
+
+
+def main():
+    image = imageio.imread(IMAGE_PATH)
+    shape = tuple(s // DOWNSCALE_FACTOR for s in image.shape)
+    # Resize in float and truncate, like the finetuning data.
+    small_image = resize(image.astype(np.float32), shape, order=1).astype(image.dtype)
+    print(f"Image shape: {image.shape}, downscaled by {DOWNSCALE_FACTOR} to: {small_image.shape}")
+
+    segmentation = segment(small_image)
+    print(f"Instances: {len(np.unique(segmentation)) - 1}")
+
+    segmentation = resize(segmentation.astype(np.uint32), image.shape, order=0)
+    imageio.imwrite(OUTPUT_PATH, segmentation, compression="zlib")
+    print(f"Saved segmentation with shape {segmentation.shape} to: {OUTPUT_PATH}")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/micro_sam/sam_annotator/util.py b/micro_sam/sam_annotator/util.py
index 6113c0247..389007643 100644
--- a/micro_sam/sam_annotator/util.py
+++ b/micro_sam/sam_annotator/util.py
@@ -1001,7 +1001,7 @@ def _batched_interactive_segmentation(predictor, points, labels, boxes, image_em
         box, point, label = prompt
         if len(negative_points) > 0:
             if point is None:
-                point, label = negative_points, negative_labels
+                point, label = np.concatenate(negative_points), np.concatenate(negative_labels)
             else:
                 point = np.concatenate([point] + negative_points)
                 label = np.concatenate([label] + negative_labels)