diff --git a/version.inc b/version.inc
index e1c5b7a323..f9cc30df79 100644
--- a/version.inc
+++ b/version.inc
@@ -3,7 +3,7 @@
 
 set(SLIC3R_APP_NAME "PrusaSlicer")
 set(SLIC3R_APP_KEY "PrusaSlicer")
-set(SLIC3R_VERSION "2.9.1-alpha0")
+set(SLIC3R_VERSION "2.9.1-alpha1")
 set(SLIC3R_BUILD_ID "PrusaSlicer-${SLIC3R_VERSION}+UNKNOWN")
 set(SLIC3R_RC_VERSION "2,9,1,0")
 set(SLIC3R_RC_VERSION_DOTS "2.9.1.0")