The port is set up to always be built with SSE2, which is only available on x86 targets. i386 targets should also not use SSE as it's not guaranteed to be supported. Here is a build error on aarch64, with similar errors on powerpc64le and armv7: FAILED: [code=1] Source/CMakeFiles/astcenc-sse2.dir/astcenccli_platform_dependents.cpp.o /usr/bin/c++ -DASTCENC_AVX=0 -DASTCENC_F16C=0 -DASTCENC_NEON=0 -DASTCENC_POPCNT=0 -DASTCENC_SSE=20 -DASTCENC_SVE=0 - DASTCENC_X86_GATHERS=0 -I/home/ports/main.ports/misc/astc-encoder/work/.build/Source -I/home/ports/main.ports/misc/a stc-encoder/work/astc-encoder-5.7.0/Source -O2 -pipe -fstack-protector-strong -fno-strict-aliasing -O2 -pipe -fstack -protector-strong -fno-strict-aliasing -DNDEBUG -std=c++14 -flto -Wall -Wextra -Wpedantic -Werror -Wshadow -Wdoub le-promotion -Wdocumentation -Wno-unknown-warning-option -Wno-c++98-compat-pedantic -Wno-c++98-c++11-compat-pedantic -Wno-float-equal -Wno-deprecated-declarations -Wno-atomic-implicit-seq-cst -Wno-overriding-option -Wno-cast-align - Wno-sign-conversion -Wno-implicit-int-conversion -Wno-shift-sign-overflow -Wno-format-nonliteral -Wno-reserved-ident ifier -Wno-cast-function-type -fno-unsafe-math-optimizations -ffp-contract=off -fno-math-errno -msse2 -mno-sse4.1 -W no-unused-command-line-argument -MD -MT Source/CMakeFiles/astcenc-sse2.dir/astcenccli_platform_dependents.cpp.o -MF Source/CMakeFiles/astcenc-sse2.dir/astcenccli_platform_dependents.cpp.o.d -o Source/CMakeFiles/astcenc-sse2.dir/astc enccli_platform_dependents.cpp.o -c /home/ports/main.ports/misc/astc-encoder/work/astc-encoder-5.7.0/Source/astcencc li_platform_dependents.cpp c++: error: unsupported option '-msse2' for target 'aarch64-unknown-freebsd16.0' c++: error: unsupported option '-mno-sse4.1' for target 'aarch64-unknown-freebsd16.0' Please fix the port. I recommend wiring SSE support into port options that are only available on x86.