diff --git a/src/RedirectablePrint.cpp b/src/RedirectablePrint.cpp
index f0ebbcc208..66a266d960 100644
--- a/src/RedirectablePrint.cpp
+++ b/src/RedirectablePrint.cpp
@@ -302,13 +302,18 @@ void RedirectablePrint::log(const char *logLevel, const char *format, ...)
     // level trace is special, two possible ways to handle it.
     if (strcmp(logLevel, MESHTASTIC_LOG_LEVEL_TRACE) == 0) {
         if (portduino_config.traceFilename != "") {
+            // Format the message rather than assuming the first vararg is a string: not every
+            // LOG_TRACE call passes one, and reading a char* that isn't there segfaults. Sized for
+            // the worst-case packet JSON (233-byte payload escaped 6x, plus metadata ~= 1.7 KB).
+            char traceBuf[2048];
             va_list arg;
             va_start(arg, format);
+            vsnprintf(traceBuf, sizeof(traceBuf), format, arg);
+            va_end(arg);
             try {
-                traceFile << va_arg(arg, char *) << std::endl;
+                traceFile << traceBuf << std::endl;
             } catch (const std::ios_base::failure &e) {
             }
-            va_end(arg);
         }
         if (portduino_config.logoutputlevel < level_trace && strcmp(logLevel, MESHTASTIC_LOG_LEVEL_TRACE) == 0) {
             return;