diff --git a/core/resources/build.properties b/core/resources/build.properties
index b82c21857..0369eda01 100644
--- a/core/resources/build.properties
+++ b/core/resources/build.properties
@@ -1,7 +1,7 @@
 
 # The OpenRocket build version
 
-build.version=13.09
+build.version=13.09dev
 
 
 # The source of the package.  When building a package for a specific