diff --git a/Lib/asyncore.py b/Lib/asyncore.py
index 37efa9bac4f..b2ee27817f4 100644
--- a/Lib/asyncore.py
+++ b/Lib/asyncore.py
@@ -600,6 +600,11 @@ class file_wrapper:
         def __init__(self, fd):
             self.fd = os.dup(fd)
 
+        def __del__(self):
+            if self.fd >= 0:
+                warnings.warn("unclosed file %r" % self, ResourceWarning)
+            self.close()
+
         def recv(self, *args):
             return os.read(self.fd, *args)
 
@@ -618,7 +623,10 @@ def getsockopt(self, level, optname, buflen=None):
         write = send
 
         def close(self):
+            if self.fd < 0:
+                return
             os.close(self.fd)
+            self.fd = -1
 
         def fileno(self):
             return self.fd
diff --git a/Lib/test/test_asyncore.py b/Lib/test/test_asyncore.py
index ef02c330002..b4f474f014d 100644
--- a/Lib/test/test_asyncore.py
+++ b/Lib/test/test_asyncore.py
@@ -413,6 +413,22 @@ def handle_read(self):
         asyncore.loop(timeout=0.01, use_poll=True, count=2)
         self.assertEqual(b"".join(data), self.d)
 
+    def test_resource_warning(self):
+        # Issue #11453
+        fd = os.open(support.TESTFN, os.O_RDONLY)
+        f = asyncore.file_wrapper(fd)
+        with support.check_warnings(('', ResourceWarning)):
+            f = None
+            support.gc_collect()
+
+    def test_close_twice(self):
+        fd = os.open(support.TESTFN, os.O_RDONLY)
+        f = asyncore.file_wrapper(fd)
+        f.close()
+        self.assertEqual(f.fd, -1)
+        # calling close twice should not fail
+        f.close()
+
 
 class BaseTestHandler(asyncore.dispatcher):
 
diff --git a/Misc/NEWS b/Misc/NEWS
index ae99bec00a9..f41ac626cc4 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -103,6 +103,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #11453: asyncore: emit a ResourceWarning when an unclosed file_wrapper
+  object is destroyed. The destructor now closes the file if needed. The
+  close() method can now be called twice: the second call does nothing.
+
 - Issue #21858: Better handling of Python exceptions in the sqlite3 module.
 
 - Issue #21476: Make sure the email.parser.BytesParser TextIOWrapper is