diff --git a/enrichment/indexed_capture.py b/enrichment/indexed_capture.py
index f02d78e..3c99341 100644
--- a/enrichment/indexed_capture.py
+++ b/enrichment/indexed_capture.py
@@ -206,7 +206,7 @@ class IndexedCapture:
         our_ssid = self.bssid_to_ssid.get(ap_bssid)
         num_bssids = len(window_ssid_to_bssids.get(our_ssid, [])) if our_ssid else 0
         avg_ssid_signal = safe_mean(window_ssid_signals.get(our_ssid, []))
-        max_ssid_signal = max(window_ssid_signals.get(our_ssid, [])) if our_ssid else 0
+        max_ssid_signal = max(window_ssid_signals.get(our_ssid, [0]))
         num_channels_ssid = len({self._channel_of_bssid(b) for b in window_ssid_to_bssids.get(our_ssid, [])}) if our_ssid else 0
         packet_count = len(packets)
 
diff --git a/runtest.sh b/runtest.sh
index e0a137b..b88462e 100755
--- a/runtest.sh
+++ b/runtest.sh
@@ -244,8 +244,24 @@ for ((COUNTER = 1; COUNTER <= NUM_TESTS; COUNTER++)); do
 
     END_TIME=$(date -Iseconds)
     
-    LISTENER_ROW=$(tail -n 1 "$LISTENER_SAMPLE_FILE")
-    echo "$START_TIME,$END_TIME,$link_level_noise,$bssid_and_bitrate,$speed_results,$FAILED_DELTA,$channel,$freq,$packet_loss,$jitter,$LocalTCPUp,$LocalTCPDown,$LocalUDPUp,$LocalUDPDown,$RemoteTCPUp,$RemoteTCPDown,$RemoteUDPUp,$RemoteUDPDown,$LISTENER_ROW" >> "$TEST_FILE"
+    if [ "$LISTENER_ENABLED" -eq 1 ] && [ -n "${LISTENER_SAMPLE_FILE:-}" ]; then
+      if [ -f "$LISTENER_SAMPLE_FILE" ]; then
+        LISTENER_ROW=$(tail -n 1 "$LISTENER_SAMPLE_FILE")
+        if [ -n "$LISTENER_ROW" ]; then
+          echo "$START_TIME,$END_TIME,$link_level_noise,$bssid_and_bitrate,$speed_results,$FAILED_DELTA,$channel,$freq,$packet_loss,$jitter,$LocalTCPUp,$LocalTCPDown,$LocalUDPUp,$LocalUDPDown,$RemoteTCPUp,$RemoteTCPDown,$RemoteUDPUp,$RemoteUDPDown,$LISTENER_ROW" >> "$TEST_FILE"
+        else
+          warn "Listener output file $LISTENER_SAMPLE_FILE was empty. Appending blank listener columns."
+          echo "$START_TIME,$END_TIME,$link_level_noise,$bssid_and_bitrate,$speed_results,$FAILED_DELTA,$channel,$freq,$packet_loss,$jitter,$LocalTCPUp,$LocalTCPDown,$LocalUDPUp,$LocalUDPDown,$RemoteTCPUp,$RemoteTCPDown,$RemoteUDPUp,$RemoteUDPDown,$(yes ',' | head -n 12 | tr -d '\n')" >> "$TEST_FILE"
+        fi
+        rm -f "$LISTENER_SAMPLE_FILE"
+      else
+        warn "Listener sample file $LISTENER_SAMPLE_FILE not found. Appending blank listener columns."
+        echo "$START_TIME,$END_TIME,$link_level_noise,$bssid_and_bitrate,$speed_results,$FAILED_DELTA,$channel,$freq,$packet_loss,$jitter,$LocalTCPUp,$LocalTCPDown,$LocalUDPUp,$LocalUDPDown,$RemoteTCPUp,$RemoteTCPDown,$RemoteUDPUp,$RemoteUDPDown,$(yes ',' | head -n 12 | tr -d '\n')" >> "$TEST_FILE"
+      fi
+    else
+      echo "$START_TIME,$END_TIME,$link_level_noise,$bssid_and_bitrate,$speed_results,$FAILED_DELTA,$channel,$freq,$packet_loss,$jitter,$LocalTCPUp,$LocalTCPDown,$LocalUDPUp,$LocalUDPDown,$RemoteTCPUp,$RemoteTCPDown,$RemoteUDPUp,$RemoteUDPDown" >> "$TEST_FILE"
+    fi
+
   done
 
   [[ "$COUNTER" -lt "$NUM_TESTS" ]] && log "Waiting $TIME_BETWEEN before next test..." && sleep "$TIME_BETWEEN"