diff --git a/xs/src/libslic3r/libslic3r.h b/xs/src/libslic3r/libslic3r.h
index 09b2b6a23e..f71481a6f7 100644
--- a/xs/src/libslic3r/libslic3r.h
+++ b/xs/src/libslic3r/libslic3r.h
@@ -6,7 +6,7 @@
 #include <iostream>
 #include <sstream>
 
-#define SLIC3R_VERSION "1.2.8"
+#define SLIC3R_VERSION "1.2.9-dev"
 
 #define EPSILON 1e-4
 #define SCALING_FACTOR 0.000001