diff --git a/hal/halarm/generic/halinit.c b/hal/halarm/generic/halinit.c
index 76adb5c1681..46feffc47d9 100644
--- a/hal/halarm/generic/halinit.c
+++ b/hal/halarm/generic/halinit.c
@@ -165,7 +165,7 @@ DbgPrintEarly(const char *fmt, ...)
     PCHAR String = Buffer;
 
     va_start(args, fmt);
-    i = vsprintf(Buffer, fmt, args);
+    i = vsnprintf(Buffer, sizeof(Buffer), fmt, args);
     va_end(args);
 
     /* Output the message */