Follow up I reinstalled Raspian Stretch and kernel-headers for 4.14.79+ and got the same error. I downloaded the previous release from here --> https://git.zx2c4.com/WireGuard/snapshot/WireGuard-0.0.20190123.zip and the error did not occur. Robert On Tue, Mar 26, 2019 at 4:21 PM Robert Ross wrote: > Details: > PiZeroW > Linux XXX 4.14.98+ #1200 Tue Feb 12 20:11:02 GMT 2019 armv6l GNU/Linux > Latest kernel-headers > Added rpi-source > > I get this error compiling on PiZeroW > > ~/WireGuard/src# make > CC [M] /root/WireGuard/src/main.o > CC [M] /root/WireGuard/src/noise.o > CC [M] /root/WireGuard/src/device.o > /root/WireGuard/src/device.c: In function 'wg_xmit': > /root/WireGuard/src/device.c:165:3: error: implicit declaration of > function 'skb_mark_not_on_list' [-Werror=implicit-function-declaration] > skb_mark_not_on_list(skb); > ^~~~~~~~~~~~~~~~~~~~ > cc1: some warnings being treated as errors > scripts/Makefile.build:326: recipe for target > '/root/WireGuard/src/device.o' failed > make[2]: *** [/root/WireGuard/src/device.o] Error 1 > Makefile:1535: recipe for target '_module_/root/WireGuard/src' failed > make[1]: *** [_module_/root/WireGuard/src] Error 2 > Makefile:37: recipe for target 'module' failed > make: *** [module] Error 2 > > TIA for any insights. Robert >