diff --git a/src/sys/flags.rs b/src/sys/flags.rs
index 87b6e40f..b7c3b32a 100644
--- a/src/sys/flags.rs
+++ b/src/sys/flags.rs
@@ -711,6 +711,16 @@ impl From<RawFlags> for IndividualFlags {
 mod tests {
     use super::*;
 
+    #[test]
+    fn default_looks_like_zero() {
+        let n = NodeFlags::default();
+        assert_eq!(n.bits(), 0);
+        assert!(n.contains(NodeFlags::NONE));
+        let s = SimplificationOptions::default();
+        assert_eq!(s.bits(), 0);
+        assert!(s.contains(SimplificationOptions::NONE));
+    }
+
     #[test]
     fn node_is_not_sample() {
         let n = NodeFlags::default();