diff --git a/src/trace.cpp b/src/trace.cpp
index 25912e3..4ef1919 100644
--- a/src/trace.cpp
+++ b/src/trace.cpp
@@ -48,7 +48,7 @@ static TraceLine &trace_line(uint16_t index)
 static void print(uint8_t severity, const char *buffer, int length)
 {
   char lin[MAX_LINE_LEN + 1];
-  int lineptr = 0;
+  unsigned int lineptr = 0;
 
   while ((0 != *buffer) && (lineptr < (sizeof(lin) - 1)))
   {