You asked for it. After a re-install. $ cat test.c #include <stdio.h> int main(void) { printf("Hello world!\n"); return 0; } $ clang test.c ld: tapi error: malformed file /Library/Developer/CommandLineTools/SDKs/MacOSX27.0.sdk/usr/lib/libSystem.B.tbd:4:20: error: unknown architecture arm64e.x1-macos, arm64e.x1-maccatalyst ] ^~~~~~~~~~~~~~~ in '/Library/Developer/CommandLineTools/SDKs/MacOSX27.0.sdk/usr/lib/libSystem.tbd' clang: error: linker command failed with exit code 1