diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7e92276..9a0e412 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -10,7 +10,8 @@ project(minetest-classic)
 # Also remember to set PROTOCOL_VERSION in clientserver.h when releasing
 set(VERSION_MAJOR 1312)
 set(VERSION_MINOR 01)
-set(VERSION_STRING "${VERSION_MAJOR}.${VERSION_MINOR}")
+set(VERSION_EXTRA ":next")
+set(VERSION_STRING "${VERSION_MAJOR}.${VERSION_MINOR}${VERSION_EXTRA}")
 
 MESSAGE(STATUS "*** Will build version ${VERSION_STRING} ***")