diff --git a/ArduCopter/ArduCopter.pde b/ArduCopter/ArduCopter.pde
index 642ce6815d..af37413e94 100644
--- a/ArduCopter/ArduCopter.pde
+++ b/ArduCopter/ArduCopter.pde
@@ -1,6 +1,6 @@
 /// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
 
-#define THISFIRMWARE "ArduCopter V3.1-rc3"
+#define THISFIRMWARE "ArduCopter V3.1-rc4"
 /*
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
diff --git a/ArduCopter/ReleaseNotes.txt b/ArduCopter/ReleaseNotes.txt
index 0a39109d90..536afb1f90 100644
--- a/ArduCopter/ReleaseNotes.txt
+++ b/ArduCopter/ReleaseNotes.txt
@@ -1,5 +1,17 @@
 ArduCopter Release Notes:
 ------------------------------------------------------------------
+ArduCopter 3.1-rc4 13-Oct-2013
+Improvements over 3.1-rc3
+1) Performance improvements to resolve APM alt hold issues for Octacopters:
+     a) SPI bus speed increased from 500khz to 8Mhz
+     b) Telemetry buffer increased to 512bytes
+     c) broke up medium and slow loops into individual scheduled tasks and increased priority of alt hold tasks
+2) AutoTune enabled by default
+3) Bug fix for Pixhawk USB connection
+4) GPS Glitch improvements:
+       a) added GPS glitch check to arming check
+       b) parameters for vehicle max acceleration (GPSGLITCH_ACCEL) and always-ok radius (GPSGLICH_RADIUS)
+------------------------------------------------------------------
 ArduCopter 3.1-rc3 09-Oct-2013
 Improvements over 3.1-rc2
 1) GPS Glitch protection - gps positions are compared with the previous gps position.  Position accepted if within 10m or copter could have reached the position with max accel of 10m/s/s.