diff --git a/actors/runtime/src/actor_error.rs b/actors/runtime/src/actor_error.rs
index c7a3949d8c..4919883c51 100644
--- a/actors/runtime/src/actor_error.rs
+++ b/actors/runtime/src/actor_error.rs
@@ -12,6 +12,9 @@ pub struct ActorError {
     msg: String,
 }
 
+// TODO: use symbolic constant for ErrAssertionFailed when it's defined.
+pub const EXIT_CODE_ERR_ASSERTION_FAILED: ExitCode = ExitCode::new(24);
+
 impl ActorError {
     /// Creates a new ActorError. This method does not check that the code is in the
     /// range of valid actor abort codes.
@@ -44,8 +47,7 @@ impl ActorError {
         Self { exit_code: ExitCode::USR_UNSPECIFIED, msg }
     }
     pub fn user_assertion_failed(msg: String) -> Self {
-        // TODO: use symbolic constant for ErrAssertionFailed when it's defined.
-        Self { exit_code: ExitCode::from(24), msg }
+        Self { exit_code: EXIT_CODE_ERR_ASSERTION_FAILED, msg }
     }
 
     /// Returns the exit code of the error.
diff --git a/actors/runtime/src/runtime/fvm.rs b/actors/runtime/src/runtime/fvm.rs
index b922504bfa..ad502e934a 100644
--- a/actors/runtime/src/runtime/fvm.rs
+++ b/actors/runtime/src/runtime/fvm.rs
@@ -23,7 +23,7 @@ use fvm_shared::{ActorID, MethodNum};
 
 use crate::runtime::actor_blockstore::ActorBlockstore;
 use crate::runtime::{ActorCode, ConsensusFault, MessageInfo, Policy, RuntimePolicy, Syscalls};
-use crate::{actor_error, ActorError, Runtime};
+use crate::{actor_error, ActorError, Runtime, EXIT_CODE_ERR_ASSERTION_FAILED};
 
 lazy_static! {
     /// Cid of the empty array Cbor bytes (`EMPTY_ARR_BYTES`).
@@ -270,6 +270,7 @@ where
                 } else {
                     // The returned code can't be simply propagated as it may be a system exit code.
                     // TODO: improve propagation once we return a RuntimeError.
+                    // Ref https://github.com/filecoin-project/builtin-actors/issues/144
                     Err(actor_error!(
                         user_assertion_failed,
                         format!(
@@ -448,7 +449,7 @@ pub fn trampoline<C: ActorCode>(params: u32) -> u32 {
     // We do this after handling the error, because the actor may have encountered an error before
     // it even could validate the caller.
     if !rt.caller_validated {
-        fvm::vm::abort(ExitCode::USR_UNSPECIFIED.value(), Some("failed to validate caller"))
+        fvm::vm::abort(EXIT_CODE_ERR_ASSERTION_FAILED, Some("failed to validate caller"))
     }
 
     // Then handle the return value.
diff --git a/actors/runtime/src/test_utils.rs b/actors/runtime/src/test_utils.rs
index 798d0067f8..33c7ab002d 100644
--- a/actors/runtime/src/test_utils.rs
+++ b/actors/runtime/src/test_utils.rs
@@ -785,7 +785,7 @@ impl Runtime<MemoryBlockstore> for MockRuntime {
         F: FnOnce(&mut C, &mut Self) -> Result<RT, ActorError>,
     {
         if self.in_transaction {
-            return Err(actor_error!(unspecified; "nested transaction"));
+            return Err(actor_error!(user_assertion_failed; "nested transaction"));
         }
         let mut read_only = self.state()?;
         self.in_transaction = true;
@@ -810,7 +810,7 @@ impl Runtime<MemoryBlockstore> for MockRuntime {
     ) -> Result<RawBytes, ActorError> {
         self.require_in_call();
         if self.in_transaction {
-            return Err(actor_error!(unspecified; "side-effect within transaction"));
+            return Err(actor_error!(user_assertion_failed; "side-effect within transaction"));
         }
 
         assert!(
@@ -855,7 +855,7 @@ impl Runtime<MemoryBlockstore> for MockRuntime {
     fn create_actor(&mut self, code_id: Cid, actor_id: ActorID) -> Result<(), ActorError> {
         self.require_in_call();
         if self.in_transaction {
-            return Err(actor_error!(unspecified; "side-effect within transaction"));
+            return Err(actor_error!(user_assertion_failed; "side-effect within transaction"));
         }
         let expect_create_actor = self
             .expectations
@@ -871,7 +871,7 @@ impl Runtime<MemoryBlockstore> for MockRuntime {
     fn delete_actor(&mut self, addr: &Address) -> Result<(), ActorError> {
         self.require_in_call();
         if self.in_transaction {
-            return Err(actor_error!(unspecified; "side-effect within transaction"));
+            return Err(actor_error!(user_assertion_failed; "side-effect within transaction"));
         }
         let exp_act = self.expectations.borrow_mut().expect_delete_actor.take();
         if exp_act.is_none() {