diff --git a/changelog.txt b/changelog.txt
index 51fec67b..7af3aeda 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -4938,3 +4938,6 @@ Improvements to the "aperiodic hat":
 Other fixes:
 - do not display relativistic modes in model list
 - an option to not display default help (in "basic interface")
+
+2023-03-26 09:41 Update 12.1m:
+- Fixed some crashes when changing the hat parameter, embedding hat, while embedding tessellation from file, using hat with fake geometry. Also fake geometry now appears in the menu for hat.
diff --git a/hyper.h b/hyper.h
index e6a0ff94..a3c7b2fa 100644
--- a/hyper.h
+++ b/hyper.h
@@ -13,8 +13,8 @@
 #define _HYPER_H_
 
 // version numbers
-#define VER "12.1l"
-#define VERNUM_HEX 0xA92C
+#define VER "12.1m"
+#define VERNUM_HEX 0xA92D
 
 #include "sysconfig.h"