diff --git a/modal/sandbox.py b/modal/sandbox.py
index aed5c8df4..883e7f202 100644
--- a/modal/sandbox.py
+++ b/modal/sandbox.py
@@ -199,7 +199,7 @@ async def create(
             _experimental_gpus=_experimental_gpus,
         )
         if client is None:
-            if app:
+            if app and app._client:
                 client = app._client
             else:
                 client = await _Client.from_env()
diff --git a/test/sandbox_test.py b/test/sandbox_test.py
index eae1613d1..4dbc865e7 100644
--- a/test/sandbox_test.py
+++ b/test/sandbox_test.py
@@ -36,6 +36,14 @@ def test_sandbox(client, servicer):
     assert sb.poll() == 42
 
 
+@skip_non_linux
+def test_app_attached_from_env(set_env_client):
+    sb = Sandbox.create("echo", "hi", app=app)
+    sb.wait()
+
+    assert sb.stdout.read() == "hi\n"
+
+
 @skip_non_linux
 def test_sandbox_mount(client, servicer, tmpdir):
     tmpdir.join("a.py").write(b"foo")