diff --git a/Grbl_Esp32/src/StackTrace/AssertionFailed.cpp b/Grbl_Esp32/src/StackTrace/AssertionFailed.cpp
index 94bec352..f1f2c1b3 100644
--- a/Grbl_Esp32/src/StackTrace/AssertionFailed.cpp
+++ b/Grbl_Esp32/src/StackTrace/AssertionFailed.cpp
@@ -35,16 +35,15 @@ AssertionFailed AssertionFailed::create(const char* condition, const char* msg,
     va_list arg;
     va_start(arg, msg);
     size_t len = vsnprintf(tmp, 255, msg, arg);
-    tmp[254]   = 0;
-
-    msg = tmp;
+    va_end(arg);
+    tmp[254] = 0;
 
     st += tmp;
 
     st += " at: ";
     st += esp_backtrace_print(10);
 
-    return AssertionFailed(st);
+    return AssertionFailed(st, tmp);
 }
 
 #else
diff --git a/Grbl_Esp32/src/StackTrace/AssertionFailed.h b/Grbl_Esp32/src/StackTrace/AssertionFailed.h
index 1a447188..7bc660e9 100644
--- a/Grbl_Esp32/src/StackTrace/AssertionFailed.h
+++ b/Grbl_Esp32/src/StackTrace/AssertionFailed.h
@@ -26,7 +26,7 @@ public:
     String stackTrace;
     String msg;
 
-    AssertionFailed(String st) : stackTrace(st) {}
+    AssertionFailed(String st, String message) : stackTrace(st), msg(message) {}
 
     static AssertionFailed create(const char* condition) { return create(condition, "Assertion failed"); }
     static AssertionFailed create(const char* condition, const char* msg, ...);