diff --git a/.circleci/config.yml b/.circleci/config.yml
index 68d02416d..7be85d7f9 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -38,6 +38,15 @@ jobs:
       - checkout
       - run: sudo pip install tox
       - run: tox -e py38
+  py39:
+    docker:
+      - image: circleci/python:3.9.0b1
+    steps:
+      # Remove IPv6 entry for localhost in Circle CI containers because it doesn't work anyway.
+      - run: sudo cp /etc/hosts /tmp; sudo sed -i '/::1/d' /tmp/hosts; sudo cp /tmp/hosts /etc
+      - checkout
+      - run: sudo pip install tox
+      - run: tox -e py39
 
 workflows:
   version: 2
@@ -53,3 +62,6 @@ workflows:
       - py38:
           requires:
             - main
+      - py39:
+          requires:
+            - main
diff --git a/.gitignore b/.gitignore
index ef0d16520..c23cf5210 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,7 @@
 *.pyc
 *.so
 .coverage
+.idea/
 .mypy_cache
 .tox
 build/
diff --git a/src/websockets/server.py b/src/websockets/server.py
index 1d8de8914..e9318a4df 100644
--- a/src/websockets/server.py
+++ b/src/websockets/server.py
@@ -714,7 +714,10 @@ async def _close(self) -> None:
         # asyncio.wait doesn't accept an empty first argument
         if self.websockets:
             await asyncio.wait(
-                [websocket.close(1001) for websocket in self.websockets],
+                [
+                    asyncio.ensure_future(websocket.close(1001))
+                    for websocket in self.websockets
+                ],
                 loop=self.loop if sys.version_info[:2] < (3, 8) else None,
             )
 
diff --git a/tox.ini b/tox.ini
index 825e34061..cc224f9c6 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist = py36,py37,py38,coverage,black,flake8,isort,mypy
+envlist = py36,py37,py38,py39,coverage,black,flake8,isort,mypy
 
 [testenv]
 commands = python -W default -m unittest {posargs}