diff --git a/stand/common/dev_net.c b/stand/common/dev_net.c
--- a/stand/common/dev_net.c
+++ b/stand/common/dev_net.c
@@ -182,6 +182,7 @@
 			setenv("boot.netif.mtu", mtu, 1);
 		}
 
+		DEBUG_PRINTF(1,("%s: netproto=%d\n", __func__, netproto));
 	}
 	netdev_opens++;
 	dev->d_opendata = &netdev_sock;
@@ -193,7 +194,7 @@
 {
 	struct devdesc *dev;
 
-	DEBUG_PRINTF(1,("%s: opens=%d\n", __func__, netdev_opens));
+	DEBUG_PRINTF(2,("%s: opens=%d\n", __func__, netdev_opens));
 
 	dev = f->f_devdata;
 	dev->d_opendata = NULL;
@@ -344,6 +345,12 @@
 	return (ret);
 }
 
+bool
+is_tftp(void)
+{
+    return (netproto == NET_TFTP);
+}
+
 /*
  * Parses the rootpath if present
  *
diff --git a/stand/libsa/mount.c b/stand/libsa/mount.c
--- a/stand/libsa/mount.c
+++ b/stand/libsa/mount.c
@@ -107,7 +107,10 @@
 		fs = file_system[i];
 		if (fs->fo_mount == NULL)
 			continue;
-
+		DEBUG_PRINTF(1,("%s: fs=%s path=%s\n",
+			__func__, fs->fs_name, path));
+		if (is_tftp())
+			break;
 		if (fs->fo_mount(dev, path, &data) != 0)
 			continue;
 
diff --git a/stand/libsa/open.c b/stand/libsa/open.c
--- a/stand/libsa/open.c
+++ b/stand/libsa/open.c
@@ -138,6 +138,8 @@
 	struct fs_ops *fs;
 	struct open_file *f;
 	int fd, i, error, besterror;
+	bool is_dir;
+	size_t n;
 	const char *file;
 
 	TSENTER();
@@ -182,8 +184,14 @@
 
 	/* pass file name to the different filesystem open routines */
 	besterror = ENOENT;
+	n = strlen(file);
+	is_dir = (n > 0 && file[n - 1] == '/');
 	for (i = 0; file_system[i] != NULL; i++) {
 		fs = file_system[i];
+		if (is_dir && is_tftp()) {
+			error = EOPNOTSUPP;
+			goto err;
+		}
 		error = (fs->fo_open)(file, f);
 		if (error == 0)
 			goto ok;
diff --git a/stand/libsa/stand.h b/stand/libsa/stand.h
--- a/stand/libsa/stand.h
+++ b/stand/libsa/stand.h
@@ -507,6 +507,9 @@
  */
 caddr_t ptov(uintptr_t);
 
+/* dev_net.c */
+bool is_tftp(void);
+
 /* features.c */
 typedef void (feature_iter_fn)(void *, const char *, const char *, bool);