diff --git a/src/interpreter/fvm4.rs b/src/interpreter/fvm4.rs
index d164f7539847..b936b0a1d460 100644
--- a/src/interpreter/fvm4.rs
+++ b/src/interpreter/fvm4.rs
@@ -10,7 +10,7 @@ use crate::chain::{
     ChainStore,
 };
 use crate::interpreter::errors::Error;
-use crate::networks::ChainConfig;
+use crate::networks::{ChainConfig, Height, NetworkChain};
 use crate::shim::{
     address::Address, gas::price_list_by_network_version, state_tree::StateTree,
     version::NetworkVersion,
@@ -181,6 +181,7 @@ impl<DB: Blockstore + Send + Sync + 'static> Consensus for ForestExterns<DB> {
                 h2
             );
         };
+
         let bh_1 = from_slice_with_fallback::<BlockHeader>(h1)?;
         let bh_2 = from_slice_with_fallback::<BlockHeader>(h2)?;
 
@@ -188,6 +189,28 @@ impl<DB: Blockstore + Send + Sync + 'static> Consensus for ForestExterns<DB> {
             bail!("no consensus fault: submitted blocks are the same");
         }
 
+        // This is a workaround for the broken calibnet chain. See:
+        // https://github.com/filecoin-project/lotus/pull/11399
+        // Basically we relax the consensus fault checks around the WatermelonFix epoch.
+        if self.chain_config.network == NetworkChain::Calibnet {
+            let watermelonfix_height = self
+                .chain_config
+                .height_infos
+                .get(Height::WatermelonFix as usize)
+                .context("Missing WatermelonFix for calibnet")?
+                .epoch;
+
+            let finality = self.chain_config.policy.chain_finality;
+
+            let is_near_upgrade = |epoch| {
+                epoch > watermelonfix_height - finality && epoch < watermelonfix_height + finality
+            };
+
+            if is_near_upgrade(bh_1.epoch()) || is_near_upgrade(bh_2.epoch()) {
+                return Ok((None, total_gas));
+            }
+        }
+
         // (1) check conditions necessary to any consensus fault
 
         if bh_1.miner_address() != bh_2.miner_address() {
diff --git a/src/state_migration/common/macros/system.rs b/src/state_migration/common/macros/system.rs
index e32181bec98c..04147e323295 100644
--- a/src/state_migration/common/macros/system.rs
+++ b/src/state_migration/common/macros/system.rs
@@ -25,8 +25,6 @@ macro_rules! impl_system {
             use $crate::state_migration::common::*;
             use $crate::utils::db::CborStoreExt;
 
-            #[allow(dead_code)] // There are cases where it's not needed in a migration.
-                                // See `nv21fix` migration.
             pub(super) fn system_migrator<BS: Blockstore>(
                 new_manifest: &BuiltinActorManifest,
             ) -> Arc<dyn ActorMigration<BS> + Send + Sync> {
diff --git a/src/state_migration/nv21fix/migration.rs b/src/state_migration/nv21fix/migration.rs
index 041f9efddf89..80a010f2efb8 100644
--- a/src/state_migration/nv21fix/migration.rs
+++ b/src/state_migration/nv21fix/migration.rs
@@ -16,7 +16,7 @@ use cid::Cid;
 use fvm_ipld_blockstore::Blockstore;
 use fvm_ipld_encoding::CborStore;
 
-use super::{verifier::Verifier, SystemStateOld};
+use super::{system, verifier::Verifier, SystemStateOld};
 use crate::state_migration::common::{migrators::nil_migrator, StateMigration};
 
 impl<BS: Blockstore> StateMigration<BS> {
@@ -45,6 +45,11 @@ impl<BS: Blockstore> StateMigration<BS> {
             self.add_migrator(code, nil_migrator(new_code))
         }
 
+        self.add_migrator(
+            current_manifest.get_system(),
+            system::system_migrator(new_manifest),
+        );
+
         Ok(())
     }
 }
@@ -90,7 +95,7 @@ impl<BS: Blockstore> PostMigrationCheck<BS> for PostMigrationVerifier {
                 );
             }
 
-            if actor_in.state != actor_out.state {
+            if actor_in.state != actor_out.state && actor_in.code != current_manifest.get_system() {
                 bail!(
                     "actor {address} state mismatch: pre-migration: {}, post-migration: {}",
                     actor_in.state,