diff --git a/src/rpc/methods/eth.rs b/src/rpc/methods/eth.rs
index b895184646da..944716c28138 100644
--- a/src/rpc/methods/eth.rs
+++ b/src/rpc/methods/eth.rs
@@ -3406,12 +3406,7 @@ where
     let state = ctx.state_manager.get_state_tree(&state_root)?;
 
     let mut entries = Vec::new();
-    let mut msg_idx = 0;
-    for ir in raw_traces {
-        if ir.msg.from == system::ADDRESS.into() {
-            continue;
-        }
-        msg_idx += 1;
+    for (msg_idx, ir) in non_system_traces_with_positions(raw_traces) {
         let tx_hash = EthGetTransactionHashByCid::handle(ctx.clone(), (ir.msg_cid,), ext).await?;
         let tx_hash = tx_hash
             .with_context(|| format!("cannot find transaction hash for cid {}", ir.msg_cid))?;
@@ -3425,6 +3420,19 @@ where
     Ok((state, entries))
 }
 
+/// Yields non-system traces paired with 0-indexed positions matching
+/// `transactionIndex` from `eth_getBlockByNumber`. System-actor messages
+/// are filtered out without consuming a position.
+fn non_system_traces_with_positions(
+    raw_traces: impl IntoIterator<Item = ApiInvocResult>,
+) -> impl Iterator<Item = (i64, ApiInvocResult)> {
+    raw_traces
+        .into_iter()
+        .filter(|ir| ir.msg.from != system::ADDRESS.into())
+        .enumerate()
+        .map(|(idx, ir)| (idx as i64, ir))
+}
+
 async fn eth_trace_block<DB>(
     ctx: &Ctx<DB>,
     ts: &Tipset,
@@ -3989,6 +3997,40 @@ mod test {
         assert_eq!(r.0, decoded.0);
     }
 
+    /// `transactionPosition` must be 0-indexed and system-actor messages must
+    /// be filtered without consuming a position.
+    #[test]
+    fn non_system_traces_with_positions_is_zero_indexed() {
+        use crate::shim::address::Address as ShimAddress;
+        use crate::shim::message::Message_v3;
+
+        let invoc_with_from = |from: ShimAddress| -> ApiInvocResult {
+            ApiInvocResult {
+                msg: Message_v3 {
+                    to: ShimAddress::new_id(1).into(),
+                    from: from.into(),
+                    ..Message_v3::default()
+                }
+                .into(),
+                ..Default::default()
+            }
+        };
+
+        let raw_traces = vec![
+            invoc_with_from(system::ADDRESS.into()),
+            invoc_with_from(ShimAddress::new_id(1000)),
+            invoc_with_from(system::ADDRESS.into()),
+            invoc_with_from(ShimAddress::new_id(1001)),
+            invoc_with_from(ShimAddress::new_id(1002)),
+        ];
+
+        let positions: Vec<i64> = non_system_traces_with_positions(raw_traces)
+            .map(|(pos, _)| pos)
+            .collect();
+
+        assert_eq!(positions, vec![0, 1, 2]);
+    }
+
     #[test]
     fn test_abi_encoding() {
         const EXPECTED: &str = "000000000000000000000000000000000000000000000000000000000000001600000000000000000000000000000000000000000000000000000000000000510000000000000000000000000000000000000000000000000000000000000060000000000000000000000000000000000000000000000000000000000000001b1111111111111111111020200301000000044444444444444444010000000000";
diff --git a/src/rpc/methods/state/types.rs b/src/rpc/methods/state/types.rs
index 4edd6a6e3575..1b062bd021f6 100644
--- a/src/rpc/methods/state/types.rs
+++ b/src/rpc/methods/state/types.rs
@@ -47,7 +47,7 @@ pub struct ForestComputeStateOutput {
 
 lotus_json_with_self!(ForestComputeStateOutput);
 
-#[derive(Debug, Serialize, Deserialize, Clone, JsonSchema)]
+#[derive(Debug, Default, Serialize, Deserialize, Clone, JsonSchema)]
 #[serde(rename_all = "PascalCase")]
 pub struct ApiInvocResult {
     #[serde(with = "crate::lotus_json")]