diff --git a/error/src/lib.rs b/error/src/lib.rs
index ec3922edd1..b00dcc6778 100644
--- a/error/src/lib.rs
+++ b/error/src/lib.rs
@@ -303,6 +303,7 @@ impl CaliptraError {
     pub const RUNTIME_DISABLE_ATTESTATION_FAILED: CaliptraError =
         CaliptraError::new_const(0x000E0011);
     pub const RUNTIME_HANDOFF_INVALID_PARM: CaliptraError = CaliptraError::new_const(0x000E0012);
+    pub const RUNTIME_SELF_TEST_IN_PROGREESS: CaliptraError = CaliptraError::new_const(0x000E0013);
 
     /// FMC Errors
     pub const FMC_GLOBAL_NMI: CaliptraError = CaliptraError::new_const(0x000F0001);
diff --git a/runtime/src/fips.rs b/runtime/src/fips.rs
index 226d80df9e..a6cdb57234 100644
--- a/runtime/src/fips.rs
+++ b/runtime/src/fips.rs
@@ -62,12 +62,21 @@ impl FipsVersionCmd {
 #[cfg(feature = "fips_self_test")]
 pub mod fips_self_test_cmd {
     use super::*;
+    use crate::RtBootStatus::{RtFipSelfTestComplete, RtFipSelfTestStarted};
     use caliptra_common::{verifier::FirmwareImageVerificationEnv, FMC_ORG, RUNTIME_ORG};
     use caliptra_drivers::ResetReason;
     use caliptra_image_verify::ImageVerifier;
     use zerocopy::AsBytes;
 
+    pub enum SelfTestStatus {
+        Idle,
+        InProgress(fn(&mut Drivers) -> CaliptraResult<()>),
+        Done,
+    }
+
     fn copy_and_verify_image(env: &mut Drivers) -> CaliptraResult<()> {
+        cprintln!("write dummy cmd");
+        env.mbox.write_cmd(0)?;
         cprintln!("set dlen");
         env.mbox
             .set_dlen(env.manifest.size + env.manifest.fmc.size + env.manifest.runtime.size);
@@ -93,23 +102,24 @@ pub mod fips_self_test_cmd {
         };
 
         let mut verifier = ImageVerifier::new(&mut venv);
-        cprintln!("verify");
+        cprintln!("Verify started");
         let _info = verifier.verify(
             &env.manifest,
             env.manifest.size + env.manifest.fmc.size + env.manifest.runtime.size,
             ResetReason::UpdateReset,
         )?;
-        cprintln!("verify done");
+        env.mbox.unlock();
+        cprintln!("[rt] Verify complete");
         Ok(())
     }
 
-    pub(crate) fn execute(env: &mut Drivers) -> CaliptraResult<MailboxResp> {
+    pub(crate) fn execute(env: &mut Drivers) -> CaliptraResult<()> {
+        caliptra_drivers::report_boot_status(RtFipSelfTestStarted.into());
         cprintln!("[rt] FIPS self test");
-        caliptra_common::wdt::stop_wdt(&mut env.soc_ifc);
-        execute_kats(env)?;
         copy_and_verify_image(env)?;
-
-        Ok(MailboxResp::default())
+        execute_kats(env)?;
+        caliptra_drivers::report_boot_status(RtFipSelfTestComplete.into());
+        Ok(())
     }
 
     /// Execute KAT for cryptographic algorithms implemented in H/W.
diff --git a/runtime/src/lib.rs b/runtime/src/lib.rs
index 4ec65364cc..a95b474557 100644
--- a/runtime/src/lib.rs
+++ b/runtime/src/lib.rs
@@ -1,6 +1,7 @@
 // Licensed under the Apache-2.0 license
 
 #![no_std]
+#![cfg_attr(not(feature = "fip-self-test"), allow(unused))]
 
 pub mod dice;
 mod disable;
@@ -24,7 +25,8 @@ pub use disable::DisableAttestationCmd;
 use dpe_crypto::DpeCrypto;
 pub use dpe_platform::{DpePlatform, VENDOR_ID, VENDOR_SKU};
 #[cfg(feature = "fips_self_test")]
-pub use fips::fips_self_test_cmd;
+pub use fips::{fips_self_test_cmd, fips_self_test_cmd::SelfTestStatus};
+
 pub use fips::{FipsShutdownCmd, FipsVersionCmd};
 
 pub use info::FwInfoCmd;
@@ -32,15 +34,18 @@ pub use invoke_dpe::InvokeDpeCmd;
 pub use stash_measurement::StashMeasurementCmd;
 pub use verify::EcdsaVerifyCmd;
 pub mod packet;
+use caliptra_common::mailbox_api::CommandId;
 use packet::Packet;
 
-use caliptra_common::mailbox_api::CommandId;
+#[cfg(feature = "fips_self_test")]
+use caliptra_common::mailbox_api::MailboxResp;
 use caliptra_common::memory_layout::{
     FHT_ORG, FHT_SIZE, FMCALIAS_TBS_ORG, FMCALIAS_TBS_SIZE, FUSE_LOG_ORG, FUSE_LOG_SIZE,
     LDEVID_TBS_ORG, LDEVID_TBS_SIZE, MAN1_ORG, MAN1_SIZE, MAN2_ORG, MAN2_SIZE, PCR_LOG_ORG,
     PCR_LOG_SIZE,
 };
 use caliptra_common::{cprintln, FirmwareHandoffTable};
+
 use caliptra_drivers::{
     CaliptraError, CaliptraResult, DataVault, Ecc384, KeyVault, Lms, Sha1, SocIfc,
 };
@@ -72,6 +77,8 @@ const RUNTIME_BOOT_STATUS_BASE: u32 = 0x600;
 pub enum RtBootStatus {
     // RtAlias Statuses
     RtReadyForCommands = RUNTIME_BOOT_STATUS_BASE,
+    RtFipSelfTestStarted = RUNTIME_BOOT_STATUS_BASE + 1,
+    RtFipSelfTestComplete = RUNTIME_BOOT_STATUS_BASE + 2,
 }
 
 impl From<RtBootStatus> for u32 {
@@ -119,6 +126,9 @@ pub struct Drivers<'a> {
     pub dpe: DpeInstance,
 
     pub pcr_bank: PcrBank,
+
+    #[cfg(feature = "fips_self_test")]
+    pub self_test_status: SelfTestStatus,
 }
 
 pub struct CptraDpeTypes;
@@ -190,6 +200,8 @@ impl<'a> Drivers<'a> {
             manifest,
             dpe,
             pcr_bank,
+            #[cfg(feature = "fips_self_test")]
+            self_test_status: SelfTestStatus::Idle,
         })
     }
 
@@ -217,7 +229,19 @@ impl<'a> Drivers<'a> {
     }
 }
 
-fn wait_for_cmd(_mbox: &mut Mailbox) {
+/// Run pending jobs and enter low power mode.
+fn goto_idle(drivers: &mut Drivers) {
+    // Run pending jobs before entering low power mode.
+    #[cfg(feature = "fips_self_test")]
+    if let SelfTestStatus::InProgress(execute) = drivers.self_test_status {
+        if drivers.mbox.lock() == false {
+            match execute(drivers) {
+                Ok(_) => drivers.self_test_status = SelfTestStatus::Done,
+                Err(e) => caliptra_drivers::report_fw_error_non_fatal(e.into()),
+            }
+        }
+    }
+
     // TODO: Enable interrupts?
     //#[cfg(feature = "riscv")]
     //unsafe {
@@ -268,7 +292,17 @@ fn handle_command(drivers: &mut Drivers) -> CaliptraResult<MboxStatusE> {
         CommandId::TEST_ONLY_HMAC384_VERIFY => HmacVerifyCmd::execute(drivers, cmd_bytes),
         CommandId::VERSION => FipsVersionCmd::execute(drivers),
         #[cfg(feature = "fips_self_test")]
-        CommandId::SELF_TEST => fips_self_test_cmd::execute(drivers),
+        CommandId::SELF_TEST => match drivers.self_test_status {
+            SelfTestStatus::Idle => {
+                drivers.self_test_status = SelfTestStatus::InProgress(fips_self_test_cmd::execute);
+                Ok(MailboxResp::default())
+            }
+            SelfTestStatus::Done => {
+                drivers.self_test_status = SelfTestStatus::Idle;
+                Ok(MailboxResp::default())
+            }
+            _ => Err(CaliptraError::RUNTIME_SELF_TEST_IN_PROGREESS),
+        },
         CommandId::SHUTDOWN => FipsShutdownCmd::execute(drivers),
         _ => Err(CaliptraError::RUNTIME_UNIMPLEMENTED_COMMAND),
     }?;
@@ -284,7 +318,7 @@ pub fn handle_mailbox_commands(drivers: &mut Drivers) -> ! {
     drivers.soc_ifc.assert_ready_for_runtime();
     caliptra_drivers::report_boot_status(RtBootStatus::RtReadyForCommands.into());
     loop {
-        wait_for_cmd(&mut drivers.mbox);
+        goto_idle(drivers);
         if drivers.mbox.is_cmd_ready() {
             // TODO : Move start/stop WDT to wait_for_cmd when NMI is implemented.
             caliptra_common::wdt::start_wdt(
@@ -301,6 +335,7 @@ pub fn handle_mailbox_commands(drivers: &mut Drivers) -> ! {
                 }
             }
             caliptra_common::wdt::stop_wdt(&mut drivers.soc_ifc);
+        } else {
         }
     }
 }
diff --git a/runtime/src/mailbox.rs b/runtime/src/mailbox.rs
index ece978dbd1..0250f0e3c4 100644
--- a/runtime/src/mailbox.rs
+++ b/runtime/src/mailbox.rs
@@ -1,7 +1,11 @@
 // Licensed under the Apache-2.0 license
 
 use caliptra_drivers::CaliptraResult;
-use caliptra_registers::mbox::{enums::MboxStatusE, MboxCsr};
+use caliptra_error::CaliptraError;
+use caliptra_registers::mbox::{
+    enums::{MboxFsmE, MboxStatusE},
+    MboxCsr,
+};
 use zerocopy::{AsBytes, LayoutVerified, Unalign};
 
 use crate::CommandId;
@@ -45,6 +49,26 @@ impl Mailbox {
         CommandId(cmd_code)
     }
 
+    pub fn lock(&mut self) -> bool {
+        let mbox = self.mbox.regs();
+        mbox.lock().read().lock()
+    }
+    pub fn unlock(&mut self) {
+        let mbox = self.mbox.regs_mut();
+        mbox.unlock().write(|_| 1.into());
+    }
+
+    pub fn write_cmd(&mut self, cmd: u32) -> CaliptraResult<()> {
+        let mbox = self.mbox.regs_mut();
+        match mbox.status().read().mbox_fsm_ps() {
+            MboxFsmE::MboxRdyForCmd => {
+                mbox.cmd().write(|_| cmd);
+                Ok(())
+            }
+            _ => Err(CaliptraError::RUNTIME_INTERNAL),
+        }
+    }
+
     pub fn user(&self) -> u32 {
         let mbox = self.mbox.regs();
         mbox.user().read()
diff --git a/test/tests/smoke_test.rs b/test/tests/smoke_test.rs
index 5c00d3dfd7..2d2348df32 100644
--- a/test/tests/smoke_test.rs
+++ b/test/tests/smoke_test.rs
@@ -412,4 +412,32 @@ fn fips_self_test() {
         &resp.as_bytes()[core::mem::size_of_val(&resp.chksum)..],
     ));
     assert_eq!(resp.fips_status, MailboxRespHeader::FIPS_STATUS_APPROVED);
+
+    // Confirm we can't re-start the FIPS self test.
+    hw.step_until_boot_status(
+        caliptra_runtime::RtBootStatus::RtFipSelfTestStarted.into(),
+        true,
+    );
+    let _resp = hw
+        .mailbox_execute(u32::from(CommandId::SELF_TEST), payload.as_bytes())
+        .unwrap_err();
+
+    hw.step_until_boot_status(
+        caliptra_runtime::RtBootStatus::RtFipSelfTestComplete.into(),
+        true,
+    );
+
+    let resp = hw
+        .mailbox_execute(u32::from(CommandId::SELF_TEST), payload.as_bytes())
+        .unwrap()
+        .unwrap();
+
+    let resp = MailboxRespHeader::read_from(resp.as_slice()).unwrap();
+    // Verify checksum and FIPS status
+    assert!(caliptra_common::checksum::verify_checksum(
+        resp.chksum,
+        0x0,
+        &resp.as_bytes()[core::mem::size_of_val(&resp.chksum)..],
+    ));
+    assert_eq!(resp.fips_status, MailboxRespHeader::FIPS_STATUS_APPROVED);
 }