diff --git a/src/atm/vision.py b/src/atm/vision.py
index 2a1016c..6821062 100644
--- a/src/atm/vision.py
+++ b/src/atm/vision.py
@@ -103,9 +103,11 @@ def find_rightmost_dot(
     diff = np.linalg.norm(roi_img.astype(np.float32) - bgr_bg, axis=2)
     mask = (diff > bg_tol).astype(np.uint8)
 
-    # Connected components → one component per dot. Anti-aliasing bridges
-    # between adjacent dots are small enough that 8-connectivity still
-    # separates them cleanly.
+    # Anti-aliasing bridges between adjacent dots can fuse the entire strip
+    # into one blob under 8-connectivity. Erode by 2px to sever those bridges
+    # before labelling — dots shrink but remain well above min_cluster_px.
+    kernel = np.ones((3, 3), dtype=np.uint8)
+    mask = cv2.erode(mask, kernel, iterations=2)
     n_labels, _labels, stats, centroids = cv2.connectedComponentsWithStats(
         mask, connectivity=8,
     )