Raspberry Pi unable to compile (kernel 6.1.74-v8+)

Since I upgrade to bookworm (Linux raspberrypi 6.1.74-v8+ #1725 SMP PREEMPT Mon Jan 22 13:35:32 GMT 2024 aarch64 GNU/Linux) I can't compile raspbee2-rtc. This is what I tried:

gwbrck@raspberrypi:~ $  sudo apt update
sudo apt install i2c-tools build-essential raspberrypi-kernel-headers
Hit:1 http://deb.debian.org/debian bookworm InRelease
Hit:2 http://deb.debian.org/debian-security bookworm-security InRelease
Hit:3 http://archive.raspberrypi.com/debian bookworm InRelease
Hit:4 http://deb.debian.org/debian bookworm-updates InRelease
Hit:5 https://download.docker.com/linux/debian bookworm InRelease
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
All packages are up to date.
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
i2c-tools is already the newest version (4.3-2+b3).
build-essential is already the newest version (12.9).
raspberrypi-kernel-headers is already the newest version (1:1.20230405-1).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
gwbrck@raspberrypi:~ $  curl -O -L https://github.com/dresden-elektronik/raspbee2-rtc/archive/master.zip
 unzip master.zip
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
100  3847    0  3847    0     0   5736      0 --:--:-- --:--:-- --:--:-- 21021
Archive:  master.zip
6fabff2ee826c004dfb17eb4a5df115e262a0157
   creating: raspbee2-rtc-master/
  inflating: raspbee2-rtc-master/LICENSE
  inflating: raspbee2-rtc-master/Makefile
  inflating: raspbee2-rtc-master/README.md
  inflating: raspbee2-rtc-master/rtc-pcf85063.service
gwbrck@raspberrypi:~ $  cd raspbee2-rtc-master
gwbrck@raspberrypi:~/raspbee2-rtc-master $ make
checking deb package dependencies...
i2c-tools
build-essential
raspberrypi-kernel-headers
download rtc-pcf85063.c for kernel version 6.1 ...
curl -O --max-time 10 https://raw.githubusercontent.com/torvalds/linux/v6.1/drivers/rtc/rtc-pcf85063.c
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 17384  100 17384    0     0  30778      0 --:--:-- --:--:-- --:--:-- 30822
build rtc module...
make -C /lib/modules/6.1.74-v8+/build M=/home/gwbrck/raspbee2-rtc-master modules
make[1]: *** /lib/modules/6.1.74-v8+/build: No such file or directory.  Stop.
make: *** [Makefile:17: build] Error 2

what am I missing? Thanks

dresden-elektronik / raspbee2-rtc

Raspberry Pi unable to compile (kernel 6.1.74-v8+) #20