+# See if <sys/ptrace.h> supports LWP names on FreeBSD
+# Older FreeBSD versions don't have the pl_tdname member of
+# `struct ptrace_lwpinfo'.
+AC_CHECK_MEMBERS([struct ptrace_lwpinfo.pl_tdname], [], [],
+ [#include <sys/ptrace.h>])
+
+# See if <sys/ptrace.h> supports syscall fields on FreeBSD. The
+# pl_syscall_code member of `struct ptrace_lwpinfo' was added in
+# FreeBSD 10.3.
+AC_CHECK_MEMBERS([struct ptrace_lwpinfo.pl_syscall_code], [], [],
+ [#include <sys/ptrace.h>])
+