diff --git a/config.env.example b/config.env.example
index d5423b2..536c25d 100644
--- a/config.env.example
+++ b/config.env.example
@@ -39,6 +39,11 @@ SCORE_SIGMOID=false
 # --- Detection ---
 # Confidence threshold – detections below this are discarded before NMS
 CONF=0.3
+# NMS IoU threshold (0-1): boxes overlapping the top box by more than this are
+# suppressed. RAISE it (e.g. 0.6-0.7) if two close/overlapping objects are being
+# merged into one and their separate boxes get suppressed. Lower = more aggressive
+# merging. Default 0.45.
+NMS_IOU=0.45
 
 # --- ByteTrack tracking ---
 # Detections with score >= this get priority matching in the first association stage
diff --git a/counter_live_rknn.py b/counter_live_rknn.py
index 4847a97..7c4d9dd 100644
--- a/counter_live_rknn.py
+++ b/counter_live_rknn.py
@@ -39,6 +39,7 @@ LINE_Y2_FRAC = float(os.getenv("LINE_Y2_FRAC", "0.66"))
 IMGSZ = int(os.getenv("IMGSZ", "320"))
 HALF = os.getenv("HALF", "false").lower() == "true"
 CONF = float(os.getenv("CONF", "0.3"))
+NMS_IOU = float(os.getenv("NMS_IOU", "0.45"))
 DEVICE = int(os.getenv("DEVICE", "0"))
 
 # RKNN NPU core mask
@@ -1055,6 +1056,7 @@ def run():
         core_mask=CORE_MASK,
         imgsz=IMGSZ,
         conf=CONF,
+        iou=NMS_IOU,
         num_classes=NUM_CLASSES,
         score_sigmoid=SCORE_SIGMOID,
     )