diff --git a/src/CoreParser.php b/src/CoreParser.php
index c0f6fd3..dc87037 100644
--- a/src/CoreParser.php
+++ b/src/CoreParser.php
@@ -105,7 +105,7 @@ class CoreParser {
         $m->snr = 0;
 
         if( $m->code == CoreProtocol::RESP_CODE_CHANNEL_MSG_RECV_V3 ) {
-            $m->snr = ord($payload) / 4;
+            $m->snr = ord($payload[$idx]) / 4;
             $idx += 1;
             // two reserved bytes
             $idx += 2;