diff --git a/darwin_pytun.c b/darwin_pytun.c
index edbf62e..96f5528 100644
--- a/darwin_pytun.c
+++ b/darwin_pytun.c
@@ -286,11 +286,13 @@ static PyObject *pytun_tuntap_down(PyObject *self) {
     memset(&req, 0, sizeof(req));
     strcpy(req.ifr_name, tuntap->name);
     if (ioctl(tuntap->fd, SIOCGIFFLAGS, &req) < 0) {
+        raise_error_from_errno();
         return NULL;
     }
     if (req.ifr_flags & IFF_UP) {
         req.ifr_flags &= ~IFF_UP;
         if (ioctl(tuntap->fd, SIOCSIFFLAGS, &req) < 0) {
+            raise_error_from_errno();
             return NULL;
         }
     }
diff --git a/pytun_pmd3/wintun.py b/pytun_pmd3/wintun.py
index fdf4f4d..77bb9e7 100644
--- a/pytun_pmd3/wintun.py
+++ b/pytun_pmd3/wintun.py
@@ -247,7 +247,10 @@ def interface_index(self) -> int:
         return self.ip_interface_entry.InterfaceIndex
 
     def close(self) -> None:
-        wintun.WintunCloseAdapter(self.handle)
+        self.down()
+        if self.handle is not None:
+            wintun.WintunCloseAdapter(self.handle)
+        self.handle = None
 
     @property
     def addr(self) -> str:
@@ -270,7 +273,8 @@ def up(self, capacity: int = DEFAULT_RING_CAPCITY) -> None:
         self.session = wintun.WintunStartSession(self.handle, capacity)
 
     def down(self) -> None:
-        wintun.WintunEndSession(self.session)
+        if self.session is not None:
+            wintun.WintunEndSession(self.session)
         self.session = None
 
     def read(self) -> bytes: