diff --git a/hooks/test_apply_dummy_mode.py b/hooks/test_apply_dummy_mode.py
new file mode 100644
index 0000000..cd8c78c
--- /dev/null
+++ b/hooks/test_apply_dummy_mode.py
@@ -0,0 +1,7 @@
+from os import environ
+
+from bundlewrap.exceptions import SkipNode
+
+def node_apply_start(repo, node, interactive=False, **kwargs):
+    if environ.get('BW_VAULT_DUMMY_MODE') or environ.get('BW_PASS_DUMMY_MODE'):
+        raise SkipNode('refusing apply because dummy mode is active')