diff --git a/ArduCopter/version.h b/ArduCopter/version.h
index 3fe0a0fa65..182ec1ef11 100644
--- a/ArduCopter/version.h
+++ b/ArduCopter/version.h
@@ -6,12 +6,12 @@
 
 #include "ap_version.h"
 
-#define THISFIRMWARE "ArduCopter V3.7.0-dev"
+#define THISFIRMWARE "ArduCopter V4.0.0-dev"
 
 // the following line is parsed by the autotest scripts
-#define FIRMWARE_VERSION 3,7,0,FIRMWARE_VERSION_TYPE_DEV
+#define FIRMWARE_VERSION 4,0,0,FIRMWARE_VERSION_TYPE_DEV
 
-#define FW_MAJOR 3
-#define FW_MINOR 7
+#define FW_MAJOR 4
+#define FW_MINOR 0
 #define FW_PATCH 0
 #define FW_TYPE FIRMWARE_VERSION_TYPE_DEV