diff --git a/proxmox-schema/src/property_string.rs b/proxmox-schema/src/property_string.rs
index 964ac4f0..20c9a30e 100644
--- a/proxmox-schema/src/property_string.rs
+++ b/proxmox-schema/src/property_string.rs
@@ -166,4 +166,5 @@ fn iterate_over_property_string() {
     assert!(iter.next().is_none());
 
     assert!(PropertyIterator::new(r#"key="open \\ value"#).next().unwrap().is_err());
+    assert!(PropertyIterator::new(r#"key="open \\ value\""#).next().unwrap().is_err());
 }