Index: sys/boot/common/Makefile
===================================================================
--- sys/boot/common/Makefile
+++ sys/boot/common/Makefile
@@ -7,4 +7,9 @@
 MAN+=	zfsloader.8
 .endif
 
+# Enable PXE TFTP or NFS support, not both.
+.if defined(LOADER_TFTP_SUPPORT)
+CFLAGS+=        -DLOADER_TFTP_SUPPORT
+.endif
+
 .include <bsd.prog.mk>
Index: sys/boot/common/dev_net.c
===================================================================
--- sys/boot/common/dev_net.c
+++ sys/boot/common/dev_net.c
@@ -402,7 +402,11 @@
 	ptr = rootpath;
 	/* Fallback for compatibility mode */
 	if (netproto == NET_NONE) {
+#ifdef LOADER_TFTP_SUPPORT
+		netproto = NET_TFTP;
+#else /* LOADER_NFS_SUPPORT */
 		netproto = NET_NFS;
+#endif
 		(void)strsep(&ptr, ":");
 		if (ptr != NULL) {
 			addr = inet_addr(rootpath);