diff --git a/actors/runtime/src/runtime/mod.rs b/actors/runtime/src/runtime/mod.rs
index 837f06ea0..97acf008d 100644
--- a/actors/runtime/src/runtime/mod.rs
+++ b/actors/runtime/src/runtime/mod.rs
@@ -21,6 +21,7 @@ use fvm_shared::{ActorID, MethodNum};
 
 pub use self::actor_code::*;
 use crate::ActorError;
+
 mod actor_code;
 
 #[cfg(feature = "runtime-wasm")]
diff --git a/actors/runtime/src/test_utils.rs b/actors/runtime/src/test_utils.rs
index 732c3a222..a2a3d673d 100644
--- a/actors/runtime/src/test_utils.rs
+++ b/actors/runtime/src/test_utils.rs
@@ -156,6 +156,7 @@ pub struct ExpectCreateActor {
     pub code_id: Cid,
     pub actor_id: ActorID,
 }
+
 #[derive(Clone, Debug)]
 pub struct ExpectedMessage {
     pub to: Address,
@@ -594,8 +595,8 @@ impl Runtime<MemoryBlockstore> for MockRuntime {
             .unwrap();
 
         assert!(expected_msg.to == to && expected_msg.method == method && expected_msg.params == params && expected_msg.value == value,
-            "expectedMessage being sent does not match expectation.\nMessage -\t to: {:?} method: {:?} value: {:?} params: {:?}\nExpected -\t {:?}",
-            to, method, value, params, expected_msg);
+                "expectedMessage being sent does not match expectation.\nMessage -\t to: {:?} method: {:?} value: {:?} params: {:?}\nExpected -\t {:?}",
+                to, method, value, params, expected_msg);
 
         {
             let mut balance = self.balance.borrow_mut();
diff --git a/fvm/src/externs/mod.rs b/fvm/src/externs/mod.rs
index 440262285..6ddc61c59 100644
--- a/fvm/src/externs/mod.rs
+++ b/fvm/src/externs/mod.rs
@@ -14,7 +14,7 @@ pub trait Consensus {
         h1: &[u8],
         h2: &[u8],
         extra: &[u8],
-    ) -> anyhow::Result<Option<ConsensusFault>>;
+    ) -> anyhow::Result<(Option<ConsensusFault>, i64)>;
 }
 
 /// Randomness provider trait
diff --git a/fvm/src/kernel/default.rs b/fvm/src/kernel/default.rs
index 465b5fc79..a8bab96b9 100644
--- a/fvm/src/kernel/default.rs
+++ b/fvm/src/kernel/default.rs
@@ -14,6 +14,7 @@ use fvm_shared::blockstore::{Blockstore, CborStore};
 use fvm_shared::commcid::{
     cid_to_data_commitment_v1, cid_to_replica_commitment_v1, data_commitment_v1_to_cid,
 };
+use fvm_shared::consensus::ConsensusFault;
 use fvm_shared::econ::TokenAmount;
 use fvm_shared::encoding::{blake2b_256, bytes_32, to_vec, RawBytes};
 use fvm_shared::error::ErrorNumber;
@@ -534,11 +535,14 @@ where
 
         // This syscall cannot be resolved inside the FVM, so we need to traverse
         // the node boundary through an extern.
-        self.call_manager
+        let (fault, gas) = self
+            .call_manager
             .externs()
             .verify_consensus_fault(h1, h2, extra)
-            .or_illegal_argument()
-            .context("fault not verified")
+            .or_illegal_argument()?;
+        self.call_manager
+            .charge_gas(GasCharge::new("verify_consensus_fault_accesses", gas, 0))?;
+        Ok(fault)
     }
 
     fn batch_verify_seals(&mut self, vis: &[SealVerifyInfo]) -> Result<Vec<bool>> {
@@ -571,7 +575,7 @@ where
                                 false
                             }
                         }
-                    },
+                    }
                     Err(e) => {
                         log::error!("seal verify internal fail (miner: {}) (err: {:?})", seal.sector_id.miner, e);
                         false
diff --git a/fvm/src/kernel/mod.rs b/fvm/src/kernel/mod.rs
index 8f55e3aec..0970daddb 100644
--- a/fvm/src/kernel/mod.rs
+++ b/fvm/src/kernel/mod.rs
@@ -19,6 +19,7 @@ mod blocks;
 pub mod default;
 
 mod error;
+
 pub use error::{ClassifyResult, Context, ExecutionError, Result, SyscallError};
 
 use crate::call_manager::{CallManager, InvocationResult};
diff --git a/fvm/src/lib.rs b/fvm/src/lib.rs
index e30e73411..8c7190730 100644
--- a/fvm/src/lib.rs
+++ b/fvm/src/lib.rs
@@ -68,6 +68,7 @@ mod test {
     struct DummyExterns;
 
     impl Externs for DummyExterns {}
+
     impl Rand for DummyExterns {
         fn get_chain_randomness(
             &self,
@@ -87,13 +88,14 @@ mod test {
             todo!()
         }
     }
+
     impl Consensus for DummyExterns {
         fn verify_consensus_fault(
             &self,
             _h1: &[u8],
             _h2: &[u8],
             _extra: &[u8],
-        ) -> anyhow::Result<Option<fvm_shared::consensus::ConsensusFault>> {
+        ) -> anyhow::Result<(Option<fvm_shared::consensus::ConsensusFault>, i64)> {
             todo!()
         }
     }
diff --git a/fvm/src/syscalls/crypto.rs b/fvm/src/syscalls/crypto.rs
index 523c465a5..8e23e107d 100644
--- a/fvm/src/syscalls/crypto.rs
+++ b/fvm/src/syscalls/crypto.rs
@@ -15,7 +15,7 @@ use fvm_shared::piece::PieceInfo;
 use fvm_shared::sector::{
     AggregateSealVerifyProofAndInfos, RegisteredSealProof, SealVerifyInfo, WindowPoStVerifyInfo,
 };
-use fvm_shared::ActorID;
+use fvm_shared::{sys, ActorID};
 use wasmtime::{Caller, Trap};
 
 use super::Context;
@@ -140,42 +140,38 @@ pub fn verify_post(
 /// the "parent grinding fault", in which case it must be the sibling of h1 (same parent tipset) and one of the
 /// blocks in the parent of h2 (i.e. h2's grandparent).
 ///
-/// Returns:
-/// - The fault type (1-3) or 0 for no fault.
-/// - The chain epoch at which the fault happened.
-/// - The actor at fault.
 pub fn verify_consensus_fault(
-    mut context: Context<'_, impl Kernel>,
+    context: Context<'_, impl Kernel>,
     h1_off: u32,
     h1_len: u32,
     h2_off: u32,
     h2_len: u32,
     extra_off: u32,
     extra_len: u32,
-) -> Result<(u32, ChainEpoch, ActorID)> {
+) -> Result<sys::out::crypto::VerifyConsensusFault> {
     let h1 = context.memory.try_slice(h1_off, h1_len)?;
     let h2 = context.memory.try_slice(h2_off, h2_len)?;
     let extra = context.memory.try_slice(extra_off, extra_len)?;
 
-    // TODO the extern should only signal an error in case there was an internal
-    //  interrupting error evaluating the consensus fault. If the outcome is
-    //  "no consensus fault was found", the extern should not error, as doing so
-    //  would interrupt execution via the Trap (at least currently).
     let ret = context.kernel.verify_consensus_fault(h1, h2, extra)?;
 
     match ret {
-        // Consensus fault detected; return the actor as a block.
-        Some(fault) => Ok((
-            fault.fault_type as u32,
-            fault.epoch,
-            fault
+        // Consensus fault detected
+        Some(fault) => Ok(sys::out::crypto::VerifyConsensusFault {
+            fault: fault.fault_type as u32,
+            epoch: fault.epoch,
+            target: fault
                 .target
                 .id()
-                .context("expected a resolved actor address")
+                .context("kernel returned non-id target address")
                 .or_fatal()?,
-        )),
+        }),
         // No consensus fault.
-        None => Ok((0, 0, 0)),
+        None => Ok(sys::out::crypto::VerifyConsensusFault {
+            fault: 0,
+            epoch: 0,
+            target: 0,
+        }),
     }
 }
 
diff --git a/sdk/src/crypto.rs b/sdk/src/crypto.rs
index 547d28730..bf38b2bed 100644
--- a/sdk/src/crypto.rs
+++ b/sdk/src/crypto.rs
@@ -97,17 +97,17 @@ pub fn verify_post(info: &WindowPoStVerifyInfo) -> SyscallResult<bool> {
 /// The parameters are all serialized block headers. The third "extra" parameter is consulted only for
 /// the "parent grinding fault", in which case it must be the sibling of h1 (same parent tipset) and one of the
 /// blocks in the parent of h2 (i.e. h2's grandparent).
-/// Returns nil and an error if the headers don't prove a fault.
+/// Returns None and an error if the headers don't prove a fault.
 #[allow(unused)]
 pub fn verify_consensus_fault(
     h1: &[u8],
     h2: &[u8],
     extra: &[u8],
 ) -> SyscallResult<Option<ConsensusFault>> {
-    let sys::crypto::out::VerifyConsensusFault {
+    let fvm_shared::sys::out::crypto::VerifyConsensusFault {
         fault,
         epoch,
-        actor,
+        target,
     } = unsafe {
         sys::crypto::verify_consensus_fault(
             h1.as_ptr(),
@@ -125,8 +125,8 @@ pub fn verify_consensus_fault(
         FromPrimitive::from_u32(fault).expect("received an invalid fault type from the runtime");
     Ok(Some(ConsensusFault {
         epoch,
+        target: Address::new_id(target),
         fault_type,
-        target: Address::new_id(actor),
     }))
 }
 
diff --git a/sdk/src/sys/crypto.rs b/sdk/src/sys/crypto.rs
index e19cade4f..74b100e81 100644
--- a/sdk/src/sys/crypto.rs
+++ b/sdk/src/sys/crypto.rs
@@ -50,7 +50,7 @@ super::fvm_syscalls! {
         h2_len: u32,
         extra_off: *const u8,
         extra_len: u32,
-    ) -> Result<self::out::VerifyConsensusFault>;
+    ) -> Result<fvm_shared::sys::out::crypto::VerifyConsensusFault>;
 
     /// Verifies an aggregated batch of sector seal proofs.
     pub fn verify_aggregate_seals(agg_off: *const u8, agg_len: u32) -> Result<i32>;
@@ -58,13 +58,3 @@ super::fvm_syscalls! {
     /// Verifies an aggregated batch of sector seal proofs.
     pub fn batch_verify_seals(batch_off: *const u8, batch_len: u32, result_off: *const u8) -> Result<()>;
 }
-
-/// Module containing multi-value out types of these syscalls.
-pub mod out {
-    #[repr(C)]
-    pub struct VerifyConsensusFault {
-        pub fault: u32,
-        pub epoch: fvm_shared::clock::ChainEpoch,
-        pub actor: fvm_shared::ActorID,
-    }
-}
diff --git a/shared/src/sys/out.rs b/shared/src/sys/out.rs
index 35c97af42..3121914dd 100644
--- a/shared/src/sys/out.rs
+++ b/shared/src/sys/out.rs
@@ -44,3 +44,15 @@ pub mod send {
         pub return_id: BlockId,
     }
 }
+
+pub mod crypto {
+    use crate::{ActorID, ChainEpoch};
+
+    #[repr(C)]
+    #[derive(Debug, Copy, Clone)]
+    pub struct VerifyConsensusFault {
+        pub fault: u32,
+        pub epoch: ChainEpoch,
+        pub target: ActorID,
+    }
+}
diff --git a/testing/conformance/src/externs.rs b/testing/conformance/src/externs.rs
index 14424f6d7..cfed1e72d 100644
--- a/testing/conformance/src/externs.rs
+++ b/testing/conformance/src/externs.rs
@@ -49,7 +49,7 @@ impl Consensus for TestExterns {
         _h1: &[u8],
         _h2: &[u8],
         _extra: &[u8],
-    ) -> anyhow::Result<Option<ConsensusFault>> {
+    ) -> anyhow::Result<(Option<ConsensusFault>, i64)> {
         todo!()
     }
 }
diff --git a/testing/conformance/src/vm.rs b/testing/conformance/src/vm.rs
index 305567e8c..8397395ab 100644
--- a/testing/conformance/src/vm.rs
+++ b/testing/conformance/src/vm.rs
@@ -337,6 +337,7 @@ where
         self.0.create_actor(code_id, actor_id)
     }
 }
+
 impl<M, C, K> BlockOps for TestKernel<K>
 where
     M: Machine,
@@ -367,6 +368,7 @@ where
         self.0.block_get(id)
     }
 }
+
 impl<M, C, K> CircSupplyOps for TestKernel<K>
 where
     M: Machine,
@@ -378,6 +380,7 @@ where
         Ok(self.1.circ_supply.clone())
     }
 }
+
 impl<M, C, K> CryptoOps for TestKernel<K>
 where
     M: Machine,
@@ -447,6 +450,7 @@ where
         Ok(true)
     }
 }
+
 impl<M, C, K> DebugOps for TestKernel<K>
 where
     M: Machine,
@@ -461,6 +465,7 @@ where
         self.0.debug_enabled()
     }
 }
+
 impl<M, C, K> GasOps for TestKernel<K>
 where
     M: Machine,
@@ -471,6 +476,7 @@ where
         self.0.charge_gas(name, compute)
     }
 }
+
 impl<M, C, K> MessageOps for TestKernel<K>
 where
     M: Machine,
@@ -493,6 +499,7 @@ where
         self.0.msg_value_received()
     }
 }
+
 impl<M, C, K> NetworkOps for TestKernel<K>
 where
     M: Machine,
@@ -511,6 +518,7 @@ where
         self.0.network_base_fee()
     }
 }
+
 impl<M, C, K> RandomnessOps for TestKernel<K>
 where
     M: Machine,
@@ -537,6 +545,7 @@ where
             .get_randomness_from_beacon(personalization, rand_epoch, entropy)
     }
 }
+
 impl<M, C, K> SelfOps for TestKernel<K>
 where
     M: Machine,
@@ -559,6 +568,7 @@ where
         self.0.self_destruct(beneficiary)
     }
 }
+
 impl<M, C, K> SendOps for TestKernel<K>
 where
     M: Machine,