diff --git a/share/mk/bsd.cpu.mk b/share/mk/bsd.cpu.mk
--- a/share/mk/bsd.cpu.mk
+++ b/share/mk/bsd.cpu.mk
@@ -391,8 +391,11 @@
 .else
 MACHINE_ABI+=	hard-float
 .endif
-# Currently all 64-bit architectures include 64 in their name (see arch(7)).
-.if ${MACHINE_ARCH:M*64*}
+# Currently all 64-bit FreeBSD architectures include 64 in their name
+# (see arch(7)).  We need a special case for cross-building from macOS
+# (which uses arm64/arm).
+.if ${MACHINE_ARCH:M*64*} || \
+    (defined(BOOTSTRAPPING) && ${.MAKE.OS} == "Darwin" && ${MACHINE} == "arm64")
 MACHINE_ABI+=  long64
 .else
 MACHINE_ABI+=  long32