diff --git a/api/src/lib.rs b/api/src/lib.rs
index a7c5d49b1c..2353a2d013 100644
--- a/api/src/lib.rs
+++ b/api/src/lib.rs
@@ -377,6 +377,21 @@ pub trait SocManager {
         mbox_read_fifo(self.soc_mbox(), buffer)?;
         Ok(cmd)
     }
+
+    /// Upload firmware to the mailbox.
+    fn upload_fw(&mut self, firmware: &[u8]) -> Result<(), CaliptraApiError> {
+        let mut resp_bytes = MboxBuffer::default();
+        let response = SocManager::mailbox_exec(
+            self,
+            CommandId::FIRMWARE_LOAD.into(),
+            firmware,
+            &mut resp_bytes,
+        )?;
+        if response.is_some() {
+            return Err(CaliptraApiError::UploadFirmwareUnexpectedResponse);
+        }
+        Ok(())
+    }
 }
 #[derive(Debug, Eq, PartialEq)]
 pub enum CaliptraApiError {
@@ -404,4 +419,5 @@ pub enum CaliptraApiError {
         expected_max: u32,
         actual: u32,
     },
+    UploadFirmwareUnexpectedResponse,
 }
diff --git a/api/src/prelude.rs b/api/src/prelude.rs
index 639fa50501..10ade3bb8c 100644
--- a/api/src/prelude.rs
+++ b/api/src/prelude.rs
@@ -3,7 +3,7 @@
 pub use crate::checksum::{calc_checksum, verify_checksum};
 
 pub use crate::mailbox::{mbox_read_fifo, mbox_write_fifo, MboxBuffer};
-pub use crate::mailbox::{MailboxReqHeader, MailboxRespHeader, Request, Response};
+pub use crate::mailbox::{CommandId, MailboxReqHeader, MailboxRespHeader, Request, Response};
 pub use crate::CaliptraApiError;
 pub use crate::MailboxRecvTxn;
 pub use crate::SocManager;
diff --git a/hw-model/src/lib.rs b/hw-model/src/lib.rs
index ebe4e741a3..24fac53a41 100644
--- a/hw-model/src/lib.rs
+++ b/hw-model/src/lib.rs
@@ -1,7 +1,6 @@
 // Licensed under the Apache-2.0 license
 
 use caliptra_api::{self as api};
-use caliptra_api_types as api_types;
 
 use caliptra_hw_model_types::{
     ErrorInjectionMode, EtrngResponse, HexBytes, HexSlice, RandomEtrngResponses, RandomNibbles,
@@ -38,7 +37,6 @@ mod model_fpga_realtime;
 mod output;
 mod rv32_builder;
 
-pub use api_types::{DeviceLifecycle, Fuses, SecurityState, U4};
 pub use caliptra_emu_bus::BusMmio;
 use output::ExitStatus;
 pub use output::Output;
@@ -328,6 +326,9 @@ impl From<CaliptraApiError> for ModelError {
                 expected_max,
                 actual,
             },
+            CaliptraApiError::UploadFirmwareUnexpectedResponse => {
+                ModelError::UploadFirmwareUnexpectedResponse
+            }
         }
     }
 }
@@ -402,9 +403,6 @@ impl Display for ModelError {
     }
 }
 
-/// Firmware Load Command Opcode
-const FW_LOAD_CMD_OPCODE: u32 = 0x4657_4C44;
-
 /// Stash Measurement Command Opcode.
 const STASH_MEASUREMENT_CMD_OPCODE: u32 = 0x4D45_4153;
 
@@ -716,7 +714,7 @@ pub trait HwModel: SocManager {
         SocManager::mailbox_exec(self, cmd, buf, resp_data).map_err(ModelError::from)
     }
 
-    fn mailbox_execute_alloc(
+    fn mailbox_execute_heap(
         &mut self,
         cmd: u32,
         buf: &[u8],
@@ -743,6 +741,11 @@ pub trait HwModel: SocManager {
         SocManager::start_mailbox_exec(self, cmd, buf).map_err(ModelError::from)
     }
 
+    fn finish_mailbox_execute_heap(&mut self) -> std::result::Result<Option<Vec<u8>>, ModelError> {
+        let mut resp_buffer = MboxBuffer::default();
+        self.finish_mailbox_execute(&mut resp_buffer)?;
+        Ok(Some(resp_buffer.as_slice().to_vec()))
+    }
     /// Wait for the response to a previous call to `start_mailbox_execute()`.
     fn finish_mailbox_execute<'r>(
         &mut self,
@@ -837,14 +840,7 @@ pub trait HwModel: SocManager {
 
     /// Upload firmware to the mailbox.
     fn upload_firmware(&mut self, firmware: &[u8]) -> Result<(), ModelError> {
-        let mut resp_bytes = MboxBuffer::default();
-        let response =
-            SocManager::mailbox_exec(self, FW_LOAD_CMD_OPCODE, firmware, &mut resp_bytes)
-                .map_err(ModelError::from)?;
-        if response.is_some() {
-            return Err(ModelError::UploadFirmwareUnexpectedResponse);
-        }
-        Ok(())
+        SocManager::upload_fw(self, firmware).map_err(ModelError::from)
     }
 
     fn wait_for_mailbox_receive<'a, 'b>(
diff --git a/hw-model/src/prelude.rs b/hw-model/src/prelude.rs
index 9fddf072b5..1a8e5bc485 100644
--- a/hw-model/src/prelude.rs
+++ b/hw-model/src/prelude.rs
@@ -1,4 +1,7 @@
 // Licensed under the Apache-2.0 license
 
 pub use crate::model_emulated::ModelEmulated;
+pub use crate::HwModel;
+pub use crate::{BootParams, DefaultHwModel, InitParams, ModelError};
 pub use caliptra_api::prelude::*;
+pub use caliptra_api_types::{DeviceLifecycle, Fuses, SecurityState, U4};
diff --git a/rom/dev/tests/rom_integration_tests/test_rom_integrity.rs b/rom/dev/tests/rom_integration_tests/test_rom_integrity.rs
index 9fddf5bf18..0208181fd6 100644
--- a/rom/dev/tests/rom_integration_tests/test_rom_integrity.rs
+++ b/rom/dev/tests/rom_integration_tests/test_rom_integrity.rs
@@ -79,7 +79,7 @@ fn test_read_rom_info_from_fmc() {
 
     // 0x1000_0008 is test-fmc/read_rom_info()
     let rom_info_from_fw = RomInfo::read_from(
-        hw.mailbox_execute_alloc(0x1000_0008, &[])
+        hw.mailbox_execute_heap(0x1000_0008, &[])
             .unwrap()
             .unwrap()
             .as_slice(),