Index: ../../sys/kern/subr_sbuf.c
===================================================================
--- ../../sys/kern/subr_sbuf.c
+++ ../../sys/kern/subr_sbuf.c
@@ -629,7 +629,7 @@
                }
                va_end(ap_copy);
 
-               if (SBUF_FREESPACE(s) >= len)
+               if (SBUF_FREESPACE(s) > len)
                        break;
                /* Cannot print with the current available space. */
                if (s->s_drain_func != NULL && s->s_len > 0)