diff --git a/client/mysqlbinlog.cc b/client/mysqlbinlog.cc
index 75b875b4f4e..9ef340197a7 100644
--- a/client/mysqlbinlog.cc
+++ b/client/mysqlbinlog.cc
@@ -396,8 +396,8 @@ static int check_header(IO_CACHE* file)
     if (buf[4] == START_EVENT)
     {
       uint event_len;
-      event_len = uint4korr(buf + 4);
-      old_format = (event_len < LOG_EVENT_HEADER_LEN + START_HEADER_LEN);
+      event_len = uint4korr(buf + EVENT_LEN_OFFSET);
+      old_format = (event_len < (LOG_EVENT_HEADER_LEN + START_HEADER_LEN));
     }
   }
   my_b_seek(file, pos);