diff --git a/lib/libc/amd64/sys/Makefile.inc b/lib/libc/amd64/sys/Makefile.inc
index 51583d35b74c..8e0d6141043c 100644
--- a/lib/libc/amd64/sys/Makefile.inc
+++ b/lib/libc/amd64/sys/Makefile.inc
@@ -11,6 +11,6 @@ MDASM=	vfork.S brk.S cerror.S exect.S getcontext.S pipe.S ptrace.S \
 NOASM=	break.o exit.o getlogin.o openbsd_poll.o sstk.o vfork.o yield.o
 
 PSEUDO=	_getlogin.o _exit.o
-.if !defined(WITHOUT_SYSCALL_COMPAT)
+.if ${MK_SYSCALL_COMPAT} != "no"
 PSEUDO+= _pread.o _pwrite.o _lseek.o _mmap.o _ftruncate.o _truncate.o
 .endif
diff --git a/lib/libc/arm/sys/Makefile.inc b/lib/libc/arm/sys/Makefile.inc
index fd251c87aa22..069aad343ac9 100644
--- a/lib/libc/arm/sys/Makefile.inc
+++ b/lib/libc/arm/sys/Makefile.inc
@@ -8,6 +8,6 @@ MDASM= Ovfork.S brk.S cerror.S pipe.S ptrace.S sbrk.S shmat.S sigreturn.S syscal
 NOASM=	break.o exit.o getlogin.o openbsd_poll.o sstk.o vfork.o yield.o
 
 PSEUDO= _exit.o _getlogin.o
-.if !defined(WITHOUT_SYSCALL_COMPAT)
+.if ${MK_SYSCALL_COMPAT} != "no"
 PSEUDO+= _pread.o _pwrite.o _lseek.o _mmap.o _ftruncate.o _truncate.o
 .endif
diff --git a/lib/libc/i386/sys/Makefile.inc b/lib/libc/i386/sys/Makefile.inc
index 9eefabca2ac3..b56183c8e3ff 100644
--- a/lib/libc/i386/sys/Makefile.inc
+++ b/lib/libc/i386/sys/Makefile.inc
@@ -15,7 +15,7 @@ MDASM=	Ovfork.S brk.S cerror.S exect.S getcontext.S pipe.S ptrace.S \
 NOASM=	break.o exit.o getlogin.o openbsd_poll.o sstk.o vfork.o yield.o
 
 PSEUDO=	_getlogin.o _exit.o
-.if !defined(WITHOUT_SYSCALL_COMPAT)
+.if ${MK_SYSCALL_COMPAT} != "no"
 PSEUDO+= _pread.o _pwrite.o _lseek.o _mmap.o _ftruncate.o _truncate.o
 .endif
 
diff --git a/lib/libc/ia64/sys/Makefile.inc b/lib/libc/ia64/sys/Makefile.inc
index 28465909a6f2..b3bacd4cd65e 100644
--- a/lib/libc/ia64/sys/Makefile.inc
+++ b/lib/libc/ia64/sys/Makefile.inc
@@ -9,6 +9,6 @@ MDASM+=	Ovfork.S brk.S cerror.S exect.S fork.S getcontext.S pipe.S ptrace.S \
 NOASM=	break.o exit.o getlogin.o openbsd_poll.o sstk.o vfork.o yield.o
 
 PSEUDO=	_getlogin.o _exit.o
-.if !defined(WITHOUT_SYSCALL_COMPAT)
+.if ${MK_SYSCALL_COMPAT} != "no"
 PSEUDO+= _pread.o _pwrite.o _lseek.o _mmap.o _ftruncate.o _truncate.o
 .endif
diff --git a/lib/libc/mips/sys/Makefile.inc b/lib/libc/mips/sys/Makefile.inc
index fc1134910646..c754f365a0b6 100644
--- a/lib/libc/mips/sys/Makefile.inc
+++ b/lib/libc/mips/sys/Makefile.inc
@@ -10,6 +10,6 @@ NOASM=	break.o exit.o ftruncate.o getlogin.o lseek.o mmap.o \
 	openbsd_poll.o pread.o pwrite.o sstk.o truncate.o vfork.o yield.o
 
 PSEUDO= _exit.o _getlogin.o
-.if !defined(WITHOUT_SYSCALL_COMPAT)
+.if ${MK_SYSCALL_COMPAT} != "no"
 PSEUDO+= _pread.o _pwrite.o _lseek.o _mmap.o _ftruncate.o _truncate.o
 .endif
diff --git a/lib/libc/powerpc/sys/Makefile.inc b/lib/libc/powerpc/sys/Makefile.inc
index 5193cc29c8f3..ad98ba1b2934 100644
--- a/lib/libc/powerpc/sys/Makefile.inc
+++ b/lib/libc/powerpc/sys/Makefile.inc
@@ -6,6 +6,6 @@ MDASM+=	brk.S cerror.S exect.S pipe.S ptrace.S sbrk.S setlogin.S
 NOASM=	break.o exit.o getlogin.o openbsd_poll.o sstk.o yield.o
 
 PSEUDO=	_getlogin.o _exit.o
-.if !defined(WITHOUT_SYSCALL_COMPAT)
+.if ${MK_SYSCALL_COMPAT} != "no"
 PSEUDO+= _pread.o _pwrite.o _lseek.o _mmap.o _ftruncate.o _truncate.o
 .endif
diff --git a/lib/libc/powerpc64/sys/Makefile.inc b/lib/libc/powerpc64/sys/Makefile.inc
index 5193cc29c8f3..ad98ba1b2934 100644
--- a/lib/libc/powerpc64/sys/Makefile.inc
+++ b/lib/libc/powerpc64/sys/Makefile.inc
@@ -6,6 +6,6 @@ MDASM+=	brk.S cerror.S exect.S pipe.S ptrace.S sbrk.S setlogin.S
 NOASM=	break.o exit.o getlogin.o openbsd_poll.o sstk.o yield.o
 
 PSEUDO=	_getlogin.o _exit.o
-.if !defined(WITHOUT_SYSCALL_COMPAT)
+.if ${MK_SYSCALL_COMPAT} != "no"
 PSEUDO+= _pread.o _pwrite.o _lseek.o _mmap.o _ftruncate.o _truncate.o
 .endif
diff --git a/lib/libc/sparc64/sys/Makefile.inc b/lib/libc/sparc64/sys/Makefile.inc
index d1754fe8caec..031af1965228 100644
--- a/lib/libc/sparc64/sys/Makefile.inc
+++ b/lib/libc/sparc64/sys/Makefile.inc
@@ -18,6 +18,6 @@ MDASM+=	brk.S cerror.S exect.S pipe.S ptrace.S sbrk.S setlogin.S sigaction.S
 NOASM=	break.o exit.o getlogin.o openbsd_poll.o sstk.o yield.o
 
 PSEUDO=	_getlogin.o _exit.o
-.if !defined(WITHOUT_SYSCALL_COMPAT)
+.if ${MK_SYSCALL_COMPAT} != "no"
 PSEUDO+= _pread.o _pwrite.o _lseek.o _mmap.o _ftruncate.o _truncate.o
 .endif
diff --git a/lib/libc/sys/Makefile.inc b/lib/libc/sys/Makefile.inc
index 86a9057786fc..07a453779677 100644
--- a/lib/libc/sys/Makefile.inc
+++ b/lib/libc/sys/Makefile.inc
@@ -21,7 +21,7 @@ PSEUDO+= _clock_gettime.o _gettimeofday.o
 
 # Sources common to both syscall interfaces:
 SRCS+=	stack_protector.c stack_protector_compat.c __error.c
-.if !defined(WITHOUT_SYSCALL_COMPAT)
+.if ${MK_SYSCALL_COMPAT} != "no"
 SYSCALL_COMPAT_SRCS=	fcntl.c ftruncate.c lseek.c mmap.c pread.c \
 	pwrite.c truncate.c
 SRCS+=	${SYSCALL_COMPAT_SRCS}
diff --git a/lib/libthr/Makefile b/lib/libthr/Makefile
index c4de29a4de0e..1c70a5e71bd2 100644
--- a/lib/libthr/Makefile
+++ b/lib/libthr/Makefile
@@ -60,7 +60,7 @@ SYMLINKS+=lib${LIB}.so ${LIBDIR}/libpthread.so
 SYMLINKS+=lib${LIB}_p.a ${LIBDIR}/libpthread_p.a
 .endif
 
-.if !defined(WITHOUT_SYSCALL_COMPAT)
+.if ${MK_SYSCALL_COMPAT} != "no"
 CFLAGS+=-DSYSCALL_COMPAT
 .endif
 
diff --git a/share/mk/bsd.own.mk b/share/mk/bsd.own.mk
index 8e2385804f5d..c682b6f227e9 100644
--- a/share/mk/bsd.own.mk
+++ b/share/mk/bsd.own.mk
@@ -334,6 +334,7 @@ __DEFAULT_YES_OPTIONS = \
     SSP \
     SVNLITE \
     SYMVER \
+    SYSCALL_COMPAT \
     SYSCONS \
     SYSINSTALL \
     TCSH \