diff --git a/src/trace.cpp b/src/trace.cpp
index 4ef1919..34239a4 100644
--- a/src/trace.cpp
+++ b/src/trace.cpp
@@ -229,14 +229,18 @@ void trace_dump(uint8_t severity, const char *prefix, uint8_t *address, size_t s
   print(severity, buffer, idx);
 }
 
-// TODO: POZOR!!! tady si nejsem jisty, zda je spravne pouziti __FlashStringHelperu v snprintf_P !!!!
 void trace_dump(uint8_t severity, const __FlashStringHelper *prefix, uint8_t *address, size_t size)
 {
   char buffer[MAX_LINE_LEN + 1 + 3];
   int idx = 0;
 
   if (prefix)
-  	idx = snprintf_P(buffer, MAX_LINE_LEN, PSTR("%s"), prefix);
+  {
+    char dummy[64];
+
+    strcpy_P(dummy, (const char *)prefix);
+    idx = snprintf_P(buffer, MAX_LINE_LEN, PSTR("%s"), dummy);
+  }
 
   while ((idx < MAX_LINE_LEN) && size)
   {