diff --git a/hyper/contrib.py b/hyper/contrib.py
index 5a580f29..ff4f8ff8 100644
--- a/hyper/contrib.py
+++ b/hyper/contrib.py
@@ -196,3 +196,8 @@ def getheaders(self, name):
         orig.msg = FakeOriginalResponse(resp.headers.iter_raw())
 
         return response
+
+    def close(self):
+        for connection in self.connections.values():
+            connection.close()
+        self.connections.clear()
diff --git a/test/test_integration.py b/test/test_integration.py
index bde7d393..6a9ece42 100644
--- a/test/test_integration.py
+++ b/test/test_integration.py
@@ -1717,3 +1717,103 @@ def socket_handler(listener):
                   timeout=(10, 0.5))
 
         self.tear_down()
+
+    def test_adapter_close(self):
+        self.set_up(secure=False)
+
+        def socket_handler(listener):
+            sock = listener.accept()[0]
+
+            # We should get the initial request.
+            data = b''
+            while not data.endswith(b'\r\n\r\n'):
+                data += sock.recv(65535)
+
+            # We need to send back a response.
+            resp = (
+                b'HTTP/1.1 201 No Content\r\n'
+                b'Server: socket-level-server\r\n'
+                b'Content-Length: 0\r\n'
+                b'Connection: close\r\n'
+                b'\r\n'
+            )
+            sock.send(resp)
+            sock.close()
+
+        self._start_server(socket_handler)
+
+        a = HTTP20Adapter()
+        s = requests.Session()
+        s.mount('http://', a)
+        r = s.get('http://%s:%s' % (self.host, self.port))
+        connections_before_close = list(a.connections.values())
+
+        # ensure that we have at least 1 connection
+        assert connections_before_close
+
+        s.close()
+
+        # check that connections cache is empty
+        assert not a.connections
+
+        # check that all connections are actually closed
+        assert all(conn._sock is None for conn in connections_before_close)
+
+        assert r.status_code == 201
+        assert len(r.headers) == 3
+        assert r.headers['server'] == 'socket-level-server'
+        assert r.headers['content-length'] == '0'
+        assert r.headers['connection'] == 'close'
+
+        assert r.content == b''
+
+        self.tear_down()
+
+    def test_adapter_close_context_manager(self):
+        self.set_up(secure=False)
+
+        def socket_handler(listener):
+            sock = listener.accept()[0]
+
+            # We should get the initial request.
+            data = b''
+            while not data.endswith(b'\r\n\r\n'):
+                data += sock.recv(65535)
+
+            # We need to send back a response.
+            resp = (
+                b'HTTP/1.1 201 No Content\r\n'
+                b'Server: socket-level-server\r\n'
+                b'Content-Length: 0\r\n'
+                b'Connection: close\r\n'
+                b'\r\n'
+            )
+            sock.send(resp)
+            sock.close()
+
+        self._start_server(socket_handler)
+
+        with requests.Session() as s:
+            a = HTTP20Adapter()
+            s.mount('http://', a)
+            r = s.get('http://%s:%s' % (self.host, self.port))
+            connections_before_close = list(a.connections.values())
+
+            # ensure that we have at least 1 connection
+            assert connections_before_close
+
+        # check that connections cache is empty
+        assert not a.connections
+
+        # check that all connections are actually closed
+        assert all(conn._sock is None for conn in connections_before_close)
+
+        assert r.status_code == 201
+        assert len(r.headers) == 3
+        assert r.headers['server'] == 'socket-level-server'
+        assert r.headers['content-length'] == '0'
+        assert r.headers['connection'] == 'close'
+
+        assert r.content == b''
+
+        self.tear_down()