I'm integrating bits of GodMode9 into my custom A9LH payload. One of the parts I need uses the C function snprintf. When I compile GodMode9, this works fine. But when I compile my own software I get a warning about an implicit declaration, and then the following error at the end of the build process: Code: /opt/devkitPro/devkitARM/bin/../lib/gcc/arm-none-eabi/5.3.0/../../../../arm-none-eabi/lib/libsysbase.a(sbrk.o): In function `_sbrk_r': (.text+0x6c): undefined reference to `__end__' collect2: error: ld returned 1 exit status make: *** [build/payload_stage2.elf] Error 1 make: *** [stage2] Error 2 If I comment out the line with snprintf, it compiles fine. I have included stdio.h in the .c file which uses this function but it hasn't made any difference. I then checked the makefile and found that it was set to c11, so I changed it to c99 but this also made no difference. I then noticed that there are some differences between the C flags in the makefiles for GodMode9 and my own programme: GodMode9 has the following flags which mine does not: -g -Wpedantic -Wcast-align -pedantic -march=armv5te -mtune=arm946e-s -fomit-frame-pointer My software has the following flags which GodMode9 does not: -MMD -MP -mcpu=arm946e-s -fno-builtin -Wno-main Does anybody know if any of these flags are responsible for me not being able to use snprintf and if so, how can I get around this? Thanks in advance!