diff --git a/mud.c b/mud.c
index 26b90dd..6fc5b29 100644
--- a/mud.c
+++ b/mud.c
@@ -1415,10 +1415,11 @@ mud_cleanup_path(struct mud *mud, uint64_t now, struct mud_path *path)
     return path->state <= MUD_DOWN;
 }
 
-static int
+int
 mud_update(struct mud *mud)
 {
     int count = 0;
+    int mtu_probe = 0;
     uint64_t rate = 0;
     size_t mtu = 0;
 
@@ -1436,6 +1437,9 @@ mud_update(struct mud *mud)
         path->ok = 0;
         count++;
 
+        if (path->mtu.probe)
+            mtu_probe = 1;
+
         if (!mud->backup && path->state == MUD_BACKUP)
             continue;
 
@@ -1482,7 +1486,10 @@ mud_update(struct mud *mud)
     mud->rate = rate;
     mud->mtu = mtu;
 
-    return count;
+    if (!count)
+        return -1;
+
+    return (mtu_probe << 1) | (mud->window < 1500);
 }
 
 int
@@ -1526,12 +1533,9 @@ mud_set_state(struct mud *mud, struct sockaddr *addr,
     return 0;
 }
 
-long
+int
 mud_send_wait(struct mud *mud)
 {
-    if (!mud_update(mud))
-        return -1;
-
     return mud->window < 1500;
 }
 
diff --git a/mud.h b/mud.h
index 9f310f5..0592ac1 100644
--- a/mud.h
+++ b/mud.h
@@ -70,6 +70,9 @@ struct mud_bad {
 struct mud *mud_create (struct sockaddr *);
 void        mud_delete (struct mud *);
 
+int mud_update    (struct mud *);
+int mud_send_wait (struct mud *);
+
 int    mud_get_fd  (struct mud *);
 size_t mud_get_mtu (struct mud *);
 int    mud_get_bad (struct mud *, struct mud_bad *);
@@ -77,8 +80,6 @@ int    mud_get_bad (struct mud *, struct mud_bad *);
 int mud_set_key (struct mud *, unsigned char *, size_t);
 int mud_get_key (struct mud *, unsigned char *, size_t *);
 
-long mud_send_wait (struct mud *);
-
 int mud_set_time_tolerance (struct mud *, unsigned long);
 int mud_set_keyx_timeout   (struct mud *, unsigned long);
 int mud_set_loss_limit     (struct mud *, unsigned);
diff --git a/test.c b/test.c
index e387cca..64b0527 100644
--- a/test.c
+++ b/test.c
@@ -62,7 +62,7 @@ main(int argc, char **argv)
 
     for (;;) {
         // mandatory, mud have lot of work to do.
-        if (mud_send_wait(mud))
+        if (mud_update(mud))
             usleep(100000); // don't use all the cpu
 
         if (client) {