diff --git a/src/asn1der.rs b/src/asn1der.rs
index e873ef3e..d3fdf7ef 100644
--- a/src/asn1der.rs
+++ b/src/asn1der.rs
@@ -93,7 +93,7 @@ impl<'a> Decode<'a> for Unit {
 // Testing the encoding and decoding of an Epoch inherently also tests the encoding and decoding of a Duration
 #[test]
 fn test_encdec() {
-    for ts_u8 in 0..=7 {
+    for ts_u8 in 0..=8 {
         let ts: TimeScale = ts_u8.into();
 
         let epoch = if ts == TimeScale::UTC {
diff --git a/tests/epoch.rs b/tests/epoch.rs
index 4becd71c..0cdd882f 100644
--- a/tests/epoch.rs
+++ b/tests/epoch.rs
@@ -1551,6 +1551,13 @@ fn test_time_of_week() {
         epoch_utc
     );
 
+    // GPST and QZSST share the same properties at all times
+    let epoch_qzsst = epoch.in_time_scale(TimeScale::QZSST);
+    assert_eq!(epoch.to_gregorian_utc(), epoch_qzsst.to_gregorian_utc());
+
+    let gps_qzss_offset = TimeScale::GPST.ref_epoch() - TimeScale::QZSST.ref_epoch();
+    assert_eq!(gps_qzss_offset.total_nanoseconds(), 0); // no offset
+
     // 06/01/1980 01:00:00 = 1H into GPST <=> (0, 3_618_000_000_000)
     let epoch = Epoch::from_time_of_week(0, 3_618_000_000_000, TimeScale::GPST);
     assert_eq!(epoch.to_gregorian_utc(), (1980, 01, 06, 01, 00, 0 + 18, 00));