diff --git a/usr.bin/top/display.c b/usr.bin/top/display.c
index 0d94e8ff7918..dc041afb8354 100644
--- a/usr.bin/top/display.c
+++ b/usr.bin/top/display.c
@@ -960,7 +960,7 @@ new_message(int type, const char *msgfmt, ...)
     va_start(args, msgfmt);
 
     /* first, format the message */
-    vsnprintf(next_msg, sizeof(next_msg), msgfmt, args);
+    vsnprintf(next_msg, strlen(next_msg), msgfmt, args);
 
     va_end(args);