diff --git a/agentstack/update.py b/agentstack/update.py
index 145623fe..8a01792f 100644
--- a/agentstack/update.py
+++ b/agentstack/update.py
@@ -68,6 +68,10 @@ def load_update_data():
 
 def should_update() -> bool:
     """Has it been longer than CHECK_EVERY since the last update check?"""
+    # Allow disabling update checks with an environment variable
+    if 'AGENTSTACK_UPDATE_DISABLE' in os.environ:
+        return False
+
     # Always check for updates in CI
     if _is_ci_environment():
         return True
diff --git a/tests/test_update.py b/tests/test_update.py
new file mode 100644
index 00000000..dab016a5
--- /dev/null
+++ b/tests/test_update.py
@@ -0,0 +1,9 @@
+import os
+import unittest
+from agentstack.update import should_update
+
+
+class UpdateTest(unittest.TestCase):
+    def test_updates_disabled_by_env_var_in_test(self):
+        assert 'AGENTSTACK_UPDATE_DISABLE' in os.environ
+        assert not should_update()
diff --git a/tox.ini b/tox.ini
index 9665ca00..6c6a966b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -15,4 +15,5 @@ commands =
     pytest -v {posargs}
     mypy: mypy agentops
 setenv = 
-    AGENTSTACK_TELEMETRY_OPT_OUT = 1
\ No newline at end of file
+    AGENTSTACK_TELEMETRY_OPT_OUT = 1
+    AGENTSTACK_UPDATE_DISABLE = 1
\ No newline at end of file