diff --git a/html/includes/graphs/device/signal.inc.php b/html/includes/graphs/device/signal.inc.php
index 5bf416ee1..d5758492e 100644
--- a/html/includes/graphs/device/signal.inc.php
+++ b/html/includes/graphs/device/signal.inc.php
@@ -2,6 +2,6 @@
  
  $class     = 'signal';
  $unit      = 'dBm';
- $unit_long = '';
+ $unit_long = 'dBm';
  
  require 'includes/graphs/device/sensor.inc.php';
\ No newline at end of file