diff --git a/supervision/detection/utils.py b/supervision/detection/utils.py
index 80743129..fb22fa1f 100644
--- a/supervision/detection/utils.py
+++ b/supervision/detection/utils.py
@@ -214,8 +214,8 @@ def mask_non_max_suppression_2(
     keep = np.ones(rows, dtype=bool)
     for i in range(rows):
         if keep[i]:
-            condition = (ious[i] > iou_threshold) & (categories == category)
-            keep[i + 1:] = np.where(condition[i + 1:], False, keep[i + 1:])
+            condition = (ious[i] > iou_threshold) & (category[i] == categories)
+            keep[i + 1 :] = np.where(condition[i + 1 :], False, keep[i + 1 :])
 
     return keep