diff --git a/listener.py b/listener.py
index 5aeace3..b7bb06d 100755
--- a/listener.py
+++ b/listener.py
@@ -18,7 +18,7 @@ aps = set()
 ap_signals = defaultdict(list)  # BSSID -> list of dBm
 ssid_map = {}  # BSSID -> SSID
 ssid_signals = defaultdict(list)  # SSID -> list of dBm
-ap_clients = defaultdict(int)
+ap_clients = defaultdict(lambda: defaultdict(int))
 target_ap_bssid = None
 
 # === Signal handling ===