diff --git a/common/defs/bitcoin/zcash.json b/common/defs/bitcoin/zcash.json
index bc57f8120..222fec050 100644
--- a/common/defs/bitcoin/zcash.json
+++ b/common/defs/bitcoin/zcash.json
@@ -46,7 +46,7 @@
     "1": 0,
     "2": 0,
     "3": 1537743641,
-    "4": 733220448
+    "4": 4122551051
   },
   "extra_data": true,
   "timestamp": false,
diff --git a/common/defs/bitcoin/zcash_testnet.json b/common/defs/bitcoin/zcash_testnet.json
index c0a89e6c8..98cdc9f95 100644
--- a/common/defs/bitcoin/zcash_testnet.json
+++ b/common/defs/bitcoin/zcash_testnet.json
@@ -42,7 +42,7 @@
     "1": 0,
     "2": 0,
     "3": 1537743641,
-    "4": 733220448
+    "4": 4122551051
   },
   "extra_data": true,
   "timestamp": false,