diff --git a/CHANGELOG.md b/CHANGELOG.md
index bc946061db..3569348833 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,9 @@ and this project adheres to
 ### Fixed
 
 - cosmwasm-std: Fix CWA-2024-002
+- cosmwasm-std: Fix `Reply` deserialization on CosmWasm 1.x chains ([#2159])
+
+[#2159]: https://github.com/CosmWasm/cosmwasm/pull/2159
 
 ### Added
 
diff --git a/contracts/reflect/schema/raw/response_to_sub_msg_result.json b/contracts/reflect/schema/raw/response_to_sub_msg_result.json
index f6c05147e3..e6ba23339b 100644
--- a/contracts/reflect/schema/raw/response_to_sub_msg_result.json
+++ b/contracts/reflect/schema/raw/response_to_sub_msg_result.json
@@ -4,13 +4,13 @@
   "description": "The result object returned to `reply`. We always get the ID from the submessage back and then must handle success and error cases ourselves.",
   "type": "object",
   "required": [
-    "gas_used",
     "id",
     "result"
   ],
   "properties": {
     "gas_used": {
-      "description": "The amount of gas used by the submessage, measured in [Cosmos SDK gas](https://github.com/CosmWasm/cosmwasm/blob/main/docs/GAS.md).",
+      "description": "The amount of gas used by the submessage, measured in [Cosmos SDK gas](https://github.com/CosmWasm/cosmwasm/blob/main/docs/GAS.md).\n\nThis only contains a useful value on chains running CosmWasm 2.0 or higher. On older chains, this field is always 0.",
+      "default": 0,
       "type": "integer",
       "format": "uint64",
       "minimum": 0.0
diff --git a/contracts/reflect/schema/reflect.json b/contracts/reflect/schema/reflect.json
index ccbaedab95..6227f412be 100644
--- a/contracts/reflect/schema/reflect.json
+++ b/contracts/reflect/schema/reflect.json
@@ -2006,13 +2006,13 @@
       "description": "The result object returned to `reply`. We always get the ID from the submessage back and then must handle success and error cases ourselves.",
       "type": "object",
       "required": [
-        "gas_used",
         "id",
         "result"
       ],
       "properties": {
         "gas_used": {
-          "description": "The amount of gas used by the submessage, measured in [Cosmos SDK gas](https://github.com/CosmWasm/cosmwasm/blob/main/docs/GAS.md).",
+          "description": "The amount of gas used by the submessage, measured in [Cosmos SDK gas](https://github.com/CosmWasm/cosmwasm/blob/main/docs/GAS.md).\n\nThis only contains a useful value on chains running CosmWasm 2.0 or higher. On older chains, this field is always 0.",
+          "default": 0,
           "type": "integer",
           "format": "uint64",
           "minimum": 0.0
diff --git a/packages/std/src/results/submessages.rs b/packages/std/src/results/submessages.rs
index 84ab978535..ac36fd0f7c 100644
--- a/packages/std/src/results/submessages.rs
+++ b/packages/std/src/results/submessages.rs
@@ -181,6 +181,10 @@ pub struct Reply {
     pub payload: Binary,
     /// The amount of gas used by the submessage,
     /// measured in [Cosmos SDK gas](https://github.com/CosmWasm/cosmwasm/blob/main/docs/GAS.md).
+    ///
+    /// This only contains a useful value on chains running CosmWasm 2.0 or higher.
+    /// On older chains, this field is always 0.
+    #[serde(default)]
     pub gas_used: u64,
     pub result: SubMsgResult,
 }
@@ -612,4 +616,29 @@ mod tests {
             }
         );
     }
+
+    #[test]
+    fn reply_serialization_cosmwasm_1() {
+        // json coming from wasmvm 1.5.0
+        let json = r#"{"id":1234,"result":{"ok":{"events":[{"type":"message","attributes":[{"key":"signer","value":"caller-addr"}]}],"data":"Zm9vYmFy"}}}"#;
+
+        let reply: Reply = from_json(json).unwrap();
+        assert_eq!(reply.id, 1234);
+        assert_eq!(reply.payload, Binary::default());
+        assert_eq!(
+            reply.result,
+            SubMsgResult::Ok(SubMsgResponse {
+                data: Some(Binary::from_base64("Zm9vYmFy").unwrap()),
+                events: vec![Event {
+                    ty: "message".to_string(),
+                    attributes: vec![Attribute {
+                        key: "signer".to_string(),
+                        value: "caller-addr".to_string()
+                    }]
+                }],
+                msg_responses: vec![]
+            })
+        );
+        assert_eq!(reply.gas_used, 0);
+    }
 }