diff --git a/setup.cfg b/setup.cfg
index 2a3bc303..de10fa55 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -21,6 +21,7 @@ filterwarnings =
   default:::uvicorn
 markers =
   copied_from(source, changes=None): mark test as copied from somewhere else, along with a description of changes made to accodomate e.g. our test setup
+  network: marks tests which require network connection. Used in 3rd-party build environments that have network disabled.
 
 [coverage:run]
 omit = venv/*, httpx/_compat.py
diff --git a/tests/client/test_proxies.py b/tests/client/test_proxies.py
index 6ea4cbe4..2817d202 100644
--- a/tests/client/test_proxies.py
+++ b/tests/client/test_proxies.py
@@ -122,6 +122,7 @@ def test_transport_for_request(url, proxies, expected):
 
 
 @pytest.mark.asyncio
+@pytest.mark.network
 async def test_async_proxy_close():
     try:
         client = httpx.AsyncClient(proxies={"https://": PROXY_URL})
@@ -130,6 +131,7 @@ async def test_async_proxy_close():
         await client.aclose()
 
 
+@pytest.mark.network
 def test_sync_proxy_close():
     try:
         client = httpx.Client(proxies={"https://": PROXY_URL})
diff --git a/tests/test_timeouts.py b/tests/test_timeouts.py
index 46a8bee8..c7a665c3 100644
--- a/tests/test_timeouts.py
+++ b/tests/test_timeouts.py
@@ -23,6 +23,7 @@ async def test_write_timeout(server):
 
 
 @pytest.mark.usefixtures("async_environment")
+@pytest.mark.network
 async def test_connect_timeout(server):
     timeout = httpx.Timeout(None, connect=1e-6)