diff --git a/uvloop/server.pyx b/uvloop/server.pyx
index 845bcfda..2dedbcc8 100644
--- a/uvloop/server.pyx
+++ b/uvloop/server.pyx
@@ -44,6 +44,9 @@ cdef class Server:
         self._loop._servers.add(self)
 
     cdef _unref(self):
+        # Server(None) is constructible from Python; guard before touching _loop.
+        if self._loop is None:
+            return
         self._loop._servers.discard(self)
 
     # Public API
@@ -77,6 +80,9 @@ cdef class Server:
     def close(self):
         cdef list servers
 
+        if self._loop is None:
+            return
+
         if self._servers is None:
             return