diff --git a/fendermint/actors/build.rs b/fendermint/actors/build.rs
index 8cc64a14b..97f78e063 100644
--- a/fendermint/actors/build.rs
+++ b/fendermint/actors/build.rs
@@ -81,6 +81,11 @@ fn main() -> Result<(), Box<dyn Error>> {
     if !result.success() {
         return Err("actor build failed".into());
     }
+
+    // make sure the output dir exists
+    std::fs::create_dir_all("output")
+        .expect("failed to create output dir for the actors_bundle.car file");
+
     let dst = Path::new("output/actors_bundle.car");
     let mut bundler = Bundler::new(dst);
     for (&pkg, id) in ACTORS.iter().zip(1u32..) {
diff --git a/fendermint/actors/chainmetadata/src/actor.rs b/fendermint/actors/chainmetadata/src/actor.rs
index baf46f23c..ecbf999bd 100644
--- a/fendermint/actors/chainmetadata/src/actor.rs
+++ b/fendermint/actors/chainmetadata/src/actor.rs
@@ -11,10 +11,11 @@ use fil_actors_runtime::runtime::{ActorCode, Runtime};
 use fil_actors_runtime::ActorDowncast;
 use fil_actors_runtime::ActorError;
 use fil_actors_runtime::Array;
+use fvm_shared::clock::ChainEpoch;
 use fvm_shared::error::ExitCode;
 
 use crate::shared::BLOCKHASHES_AMT_BITWIDTH;
-use crate::{ConstructorParams, Method, State};
+use crate::{ConstructorParams, Method, PushBlockParams, State};
 
 #[cfg(feature = "fil-actor")]
 fil_actors_runtime::wasm_trampoline!(Actor);
@@ -42,7 +43,7 @@ impl Actor {
         Ok(())
     }
 
-    fn push_block(rt: &impl Runtime, block: Cid) -> Result<(), ActorError> {
+    fn push_block(rt: &impl Runtime, params: PushBlockParams) -> Result<(), ActorError> {
         rt.validate_immediate_caller_is(std::iter::once(&SYSTEM_ACTOR_ADDR))?;
 
         rt.transaction(|st: &mut State, rt| {
@@ -56,7 +57,7 @@ impl Actor {
 
             // push the block to the AMT
             blockhashes
-                .set(rt.curr_epoch().try_into().unwrap(), block.to_string())
+                .set(params.epoch as u64, params.block.to_string())
                 .unwrap();
 
             // remove the oldest block if the AMT is full
@@ -87,7 +88,7 @@ impl Actor {
         Ok(state.lookback_len)
     }
 
-    fn block_cid(rt: &impl Runtime, rewind: u64) -> Result<Cid, ActorError> {
+    fn block_cid(rt: &impl Runtime, epoch: ChainEpoch) -> Result<Option<Cid>, ActorError> {
         let st: State = rt.state()?;
 
         // load the blockhashes AMT
@@ -98,20 +99,25 @@ impl Actor {
             )
         })?;
 
-        let blockhash: &String = blockhashes
-            .get(blockhashes.count() - rewind - 1)
-            .unwrap()
-            .unwrap();
+        // get the block cid from the AMT, if it does not exist return None
+        let blockhash: &String = match blockhashes.get(epoch as u64).unwrap() {
+            Some(v) => v,
+            None => {
+                return Ok(None);
+            }
+        };
 
-        Cid::from_str(blockhash.as_str()).map_err(|_| {
-            ActorError::unchecked(
+        // return the blockhash as a cid, or an error if the cid is invalid
+        match Cid::from_str(blockhash.as_str()) {
+            Ok(cid) => Ok(Some(cid)),
+            Err(_) => Err(ActorError::unchecked(
                 ExitCode::USR_ILLEGAL_STATE,
                 format!(
-                    "failed to parse cid, hash: {}, rewind: {}",
-                    blockhash, rewind
+                    "failed to parse cid, blockhash: {}, epoch: {}",
+                    blockhash, epoch
                 ),
-            )
-        })
+            )),
+        }
     }
 }
 
diff --git a/fendermint/actors/chainmetadata/src/shared.rs b/fendermint/actors/chainmetadata/src/shared.rs
index a930a7c5a..4daf88f49 100644
--- a/fendermint/actors/chainmetadata/src/shared.rs
+++ b/fendermint/actors/chainmetadata/src/shared.rs
@@ -3,7 +3,7 @@
 
 use cid::Cid;
 use fvm_ipld_encoding::tuple::{Deserialize_tuple, Serialize_tuple};
-use fvm_shared::METHOD_CONSTRUCTOR;
+use fvm_shared::{clock::ChainEpoch, METHOD_CONSTRUCTOR};
 use num_derive::FromPrimitive;
 
 // The state is a stores `blockhashes` in an AMT containing the blockhashes of the
@@ -28,6 +28,12 @@ pub struct ConstructorParams {
     pub lookback_len: u64,
 }
 
+#[derive(Default, Debug, Serialize_tuple, Deserialize_tuple)]
+pub struct PushBlockParams {
+    pub epoch: ChainEpoch,
+    pub block: Cid,
+}
+
 #[derive(FromPrimitive)]
 #[repr(u64)]
 pub enum Method {
diff --git a/fendermint/vm/interpreter/src/fvm/exec.rs b/fendermint/vm/interpreter/src/fvm/exec.rs
index 1b32497a8..79d91aa1d 100644
--- a/fendermint/vm/interpreter/src/fvm/exec.rs
+++ b/fendermint/vm/interpreter/src/fvm/exec.rs
@@ -85,8 +85,12 @@ where
 
         // Push the current block hash to the chainmetadata actor
         //
-        let block_cid = fendermint_vm_message::cid(&state.block_hash().unwrap()).unwrap();
-        let params = fvm_ipld_encoding::RawBytes::serialize(block_cid)?;
+        let params = fvm_ipld_encoding::RawBytes::serialize(
+            fendermint_actor_chainmetadata::PushBlockParams {
+                epoch: height,
+                block: fendermint_vm_message::cid(&state.block_hash().unwrap()).unwrap(),
+            },
+        )?;
         let msg = FvmMessage {
             from: system::SYSTEM_ACTOR_ADDR,
             to: fvm_shared::address::Address::new_id(fendermint_actors::CHAINMETADATA_ACTOR_ID),