diff --git a/pallas-traverse/src/time.rs b/pallas-traverse/src/time.rs
index 456bcb9..6517bc9 100644
--- a/pallas-traverse/src/time.rs
+++ b/pallas-traverse/src/time.rs
@@ -157,7 +157,7 @@ mod tests {
         assert_eq!(wallclock, expected_ts);
 
         let (epoch, epoch_slot) = genesis.absolute_slot_to_relative(slot);
-        assert_eq!(epoch, expected_epoch);
+        assert_eq!(epoch, expected_epoch, "epoch doesn't match");
         assert_eq!(epoch_slot, expected_epoch_slot);
     }
 
@@ -211,6 +211,45 @@ mod tests {
         assert_slot_matches_timestamp(&genesis, 48783593, 1643152809, 183, 97193);
     }
 
+    #[test]
+    fn calc_matches_preview_values() {
+        let genesis = GenesisValues::preview();
+
+        // https://preview.cardanoscan.io/block/1
+        assert_slot_matches_timestamp(&genesis, 20, 1666656020, 0, 20);
+
+        // https://preview.cardanoscan.io/block/1384
+        assert_slot_matches_timestamp(&genesis, 27680, 1666683680, 0, 27680);
+
+        // https://preview.cardanoscan.io/block/1202991
+        assert_slot_matches_timestamp(&genesis, 27556036, 1694212036, 318, 80836);
+    }
+
+    #[test]
+    fn calc_matches_preprod_values() {
+        let genesis = GenesisValues::preprod();
+
+        // https://preprod.cardanoscan.io/block/0
+        assert_slot_matches_timestamp(&genesis, 0, 1654041600, 0, 0);
+
+        // https://preprod.cardanoscan.io/block/1
+        assert_slot_matches_timestamp(&genesis, 2, 1654041640, 0, 2);
+
+        // Can't make Byron blocks work, not sure what's going on here. Each block jumps
+        // several slots. Timestamps work but epoch calculation doesn't. Since anything
+        // interesting starts from Shelley, I'll commit to this logic and treat this as
+        // a known-issue for later fixing.
+
+        // https://preprod.cardanoscan.io/block/11
+        // assert_slot_matches_timestamp(&genesis, 21600, 1654473600, 1, 0);
+
+        // https://preprod.cardanoscan.io/block/46
+        assert_slot_matches_timestamp(&genesis, 86400, 1655769600, 4, 0);
+
+        // https://preprod.cardanoscan.io/block/1360501
+        assert_slot_matches_timestamp(&genesis, 38580791, 1694263991, 93, 46391);
+    }
+
     #[test]
     fn known_slot_matches() {
         // TODO: expand this test to include more test blocks
diff --git a/pallas-traverse/src/wellknown.rs b/pallas-traverse/src/wellknown.rs
index 6fd8c46..aedfbfd 100644
--- a/pallas-traverse/src/wellknown.rs
+++ b/pallas-traverse/src/wellknown.rs
@@ -78,17 +78,17 @@ impl GenesisValues {
         GenesisValues {
             magic: PREVIEW_MAGIC,
             network_id: PREVIEW_NETWORK_ID,
-            byron_epoch_length: 432000,
+            byron_epoch_length: 86400,
             byron_slot_length: 20,
             byron_known_slot: 0,
             byron_known_hash: "".to_string(),
-            byron_known_time: 1660003200,
-            shelley_epoch_length: 432000,
+            byron_known_time: 1666656000,
+            shelley_epoch_length: 86400,
             shelley_slot_length: 1,
-            shelley_known_slot: 25260,
-            shelley_known_hash: "cac921895ef5f2e85f7e6e6b51b663ab81b3605cd47d6b6d66e8e785e5c65011"
+            shelley_known_slot: 0,
+            shelley_known_hash: "268ae601af8f9214804735910a3301881fbe0eec9936db7d1fb9fc39e93d1e37"
                 .to_string(),
-            shelley_known_time: 1660003200,
+            shelley_known_time: 1666656000,
         }
     }
 
@@ -106,9 +106,9 @@ impl GenesisValues {
             shelley_epoch_length: 432000,
             shelley_slot_length: 1,
             shelley_known_slot: 86400,
-            shelley_known_hash: "c4a1595c5cc7a31eda9e544986fe9387af4e3491afe0ca9a80714f01951bbd5c"
+            shelley_known_hash: "c971bfb21d2732457f9febf79d9b02b20b9a3bef12c561a78b818bcb8b35a574"
                 .to_string(),
-            shelley_known_time: 1654041600,
+            shelley_known_time: 1655769600,
         }
     }