diff --git a/src/trace.cpp b/src/trace.cpp
index 34239a4..5e25c4f 100644
--- a/src/trace.cpp
+++ b/src/trace.cpp
@@ -24,7 +24,7 @@ struct TraceLine
 static TraceLine _lines[MAX_TRACE_LINES];
 static uint16_t _lines_index = 0;
 static uint16_t _lines_count = 0;
-static int _modified = 0;
+static volatile int _modified = 0;
 static AsyncWebSocket *_wss = NULL; // webovy soket pro trasovani
 static Interval _tint; // interval pro casovani stopare
 
@@ -276,6 +276,7 @@ void trace_poll()
         { // .. a vyprsel timeout pro obcerstvovani
           String log;
 
+          _modified = 0; // rusime pozadavek na odeslani novych dat
           if (log.reserve((MAX_TRACE_LINES * MAX_LINE_LEN) + (MAX_TRACE_LINES * 50)))
           {
             log = F("{\"type\":\"trace\",\"data\":[");
@@ -285,7 +286,6 @@ void trace_poll()
           }
           else
             _wss->textAll(F("{\"type\":\"trace\",\"text\":\"Memory error\"}"));
-          _modified = 0; // rusime pozadavek na odeslani novych dat
           _tint.set(TRACE_CHECK_INTERVAL);
         }
       }