diff --git a/scripts/flash_usb.py b/scripts/flash_usb.py
index f1106474..9f1a7ea6 100755
--- a/scripts/flash_usb.py
+++ b/scripts/flash_usb.py
@@ -17,12 +17,12 @@ def enter_bootloader(device):
         fcntl.ioctl(fd, termios.TIOCMBIS, struct.pack('I', termios.TIOCM_DTR))
         t = termios.tcgetattr(fd)
         t[4] = t[5] = termios.B1200
+        sys.stderr.write("Entering bootloader on %s\n" % (device,))
         termios.tcsetattr(fd, termios.TCSANOW, t)
         fcntl.ioctl(fd, termios.TIOCMBIC, struct.pack('I', termios.TIOCM_DTR))
         f.close()
     except (IOError, OSError) as e:
         pass
-    time.sleep(1.0)
 
 # Translate a serial device name to a stable serial name in /dev/serial/by-path/
 def translate_serial_to_tty(device):
@@ -45,14 +45,37 @@ def translate_serial_to_usb_path(device):
     m = ttypath_r.match(lname)
     if m is None:
         raise error("Unable to find tty usb device")
-    return m.group("path")
+    devpath = os.path.realpath("/sys/class/tty/%s/device" % (fname,))
+    return m.group("path"), devpath
+
+# Wait for a given path to appear
+def wait_path(path, alt_path=None):
+    time.sleep(.100)
+    start_alt_path = None
+    end_time = time.time() + 4.0
+    while 1:
+        time.sleep(0.100)
+        cur_time = time.time()
+        if os.path.exists(path):
+            sys.stderr.write("Device reconnect on %s\n" % (path,))
+            time.sleep(0.100)
+            return path
+        if alt_path is not None and os.path.exists(alt_path):
+            if start_alt_path is None:
+                start_alt_path = cur_time
+                continue
+            if cur_time >= start_alt_path + 0.300:
+                sys.stderr.write("Device reconnect on alt path %s\n" % (
+                    alt_path,))
+                return alt_path
+        if cur_time > end_time:
+            return path
 
 # Flash via a call to bossac
 def flash_bossac(device, binfile, extra_flags=[]):
     ttyname, pathname = translate_serial_to_tty(device)
     enter_bootloader(pathname)
-    if os.path.exists(ttyname) and not os.path.exists(pathname):
-        pathname = ttyname
+    pathname = wait_path(pathname, ttyname)
     baseargs = ["lib/bossac/bin/bossac", "-U", "-p", pathname]
     args = baseargs + extra_flags + ["-w", binfile, "-v"]
     sys.stderr.write(" ".join(args) + '\n\n')
@@ -64,7 +87,7 @@ def flash_bossac(device, binfile, extra_flags=[]):
         try:
             subprocess.check_output(args, stderr=subprocess.STDOUT)
             if "-b" not in extra_flags:
-                time.sleep(1.)
+                wait_path(pathname)
                 subprocess.check_output(args, stderr=subprocess.STDOUT)
         except subprocess.CalledProcessError as e:
             pass
@@ -85,8 +108,9 @@ def flash_dfuutil(device, binfile, extra_flags=[], sudo=True):
     if hexfmt_r.match(device.strip()):
         call_dfuutil(["-d", ","+device.strip()] + extra_flags, binfile, sudo)
         return
-    buspath = translate_serial_to_usb_path(device)
+    buspath, devpath = translate_serial_to_usb_path(device)
     enter_bootloader(device)
+    pathname = wait_path(devpath)
     call_dfuutil(["-p", buspath] + extra_flags, binfile, sudo)