diff --git a/cddl/lib/libzfs/Makefile b/cddl/lib/libzfs/Makefile
--- a/cddl/lib/libzfs/Makefile
+++ b/cddl/lib/libzfs/Makefile
@@ -88,6 +88,7 @@
 SHLIB_MAJOR= 4
 CSTD=	c99
 CFLAGS+= -DIN_BASE
+CFLAGS+= -DIN_FREEBSD_BASE
 CFLAGS+= -I${SRCTOP}/sys/contrib/openzfs/include
 CFLAGS+= -I${SRCTOP}/sys/contrib/openzfs/include/os/freebsd
 CFLAGS+= -I${SRCTOP}/sys/contrib/openzfs/lib/libspl/include