diff --git a/src/libslic3r/libslic3r.h b/src/libslic3r/libslic3r.h
index 67f6db7221..ec0aa8ace9 100644
--- a/src/libslic3r/libslic3r.h
+++ b/src/libslic3r/libslic3r.h
@@ -17,8 +17,8 @@
 #include "libslic3r_version.h"
 
 // Profiles for the alpha are stored into the PrusaSlicer-alpha directory to not mix with the current release.
-   #define SLIC3R_APP_FULL_NAME SLIC3R_APP_KEY
-// #define SLIC3R_APP_FULL_NAME SLIC3R_APP_KEY "-alpha"
+// #define SLIC3R_APP_FULL_NAME SLIC3R_APP_KEY
+   #define SLIC3R_APP_FULL_NAME SLIC3R_APP_KEY "-alpha"
 // #define SLIC3R_APP_FULL_NAME SLIC3R_APP_KEY "-beta"
 
 
diff --git a/version.inc b/version.inc
index 1162128203..e1c5b7a323 100644
--- a/version.inc
+++ b/version.inc
@@ -3,7 +3,7 @@
 
 set(SLIC3R_APP_NAME "PrusaSlicer")
 set(SLIC3R_APP_KEY "PrusaSlicer")
-set(SLIC3R_VERSION "2.9.0")
+set(SLIC3R_VERSION "2.9.1-alpha0")
 set(SLIC3R_BUILD_ID "PrusaSlicer-${SLIC3R_VERSION}+UNKNOWN")
-set(SLIC3R_RC_VERSION "2,9,0,0")
-set(SLIC3R_RC_VERSION_DOTS "2.9.0.0")
+set(SLIC3R_RC_VERSION "2,9,1,0")
+set(SLIC3R_RC_VERSION_DOTS "2.9.1.0")