diff --git a/buildtools/version.py b/buildtools/version.py
index c9077a64..06d64337 100644
--- a/buildtools/version.py
+++ b/buildtools/version.py
@@ -26,7 +26,7 @@ VER_MAJOR        = 4
 VER_MINOR        = 0
 VER_RELEASE      = 0
 
-VER_FLAGS        = "a3"     # wxPython release flags
+VER_FLAGS        = "a4"     # wxPython release flags
 
 # The VER_FLAGS value is appended to the version number constructed from the
 # first 3 components and should be set according to the following patterns.