diff --git a/sw-emulator/lib/periph/Cargo.toml b/sw-emulator/lib/periph/Cargo.toml
index 81972ab11d..0e8b568471 100644
--- a/sw-emulator/lib/periph/Cargo.toml
+++ b/sw-emulator/lib/periph/Cargo.toml
@@ -19,7 +19,7 @@ caliptra-emu-derive.workspace = true
 caliptra-emu-types.workspace = true
 caliptra-hw-model-types.workspace = true
 caliptra-registers.workspace = true
-fips204.workspace = true
+fips204 = { workspace = true, optional = true }
 lazy_static.workspace = true
 rand.workspace = true
 sha3.workspace = true
@@ -29,3 +29,4 @@ zerocopy.workspace = true
 
 [features]
 "hw-1.0" = []
+"hw-2.x" = ["dep:fips204"]
diff --git a/sw-emulator/lib/periph/src/lib.rs b/sw-emulator/lib/periph/src/lib.rs
index 157470cf4b..59532d8375 100644
--- a/sw-emulator/lib/periph/src/lib.rs
+++ b/sw-emulator/lib/periph/src/lib.rs
@@ -25,6 +25,7 @@ mod hmac_sha384;
 mod iccm;
 mod key_vault;
 mod mailbox;
+#[cfg(feature = "hw-2.x")]
 mod ml_dsa87;
 mod root_bus;
 mod sha512_acc;
diff --git a/sw-emulator/lib/periph/src/root_bus.rs b/sw-emulator/lib/periph/src/root_bus.rs
index 87a0e87a07..c0532a150d 100644
--- a/sw-emulator/lib/periph/src/root_bus.rs
+++ b/sw-emulator/lib/periph/src/root_bus.rs
@@ -12,11 +12,12 @@ Abstract:
 
 --*/
 
+#[cfg(feature = "hw-2.x")]
+use crate::ml_dsa87::MlDsa87;
 use crate::MailboxRequester;
 use crate::{
     helpers::words_from_bytes_be,
     iccm::Iccm,
-    ml_dsa87::MlDsa87,
     soc_reg::{DebugManufService, SocRegistersExternal},
     AsymEcc384, Csrng, Doe, EmuCtrl, HashSha256, HashSha512, HmacSha384, KeyVault, MailboxExternal,
     MailboxInternal, MailboxRam, Sha512Accelerator, SocRegistersInternal, Uart,
@@ -268,6 +269,7 @@ pub struct CaliptraRootBus {
     #[peripheral(offset = 0x1002_8000, mask = 0x0000_7fff)]
     pub sha256: HashSha256,
 
+    #[cfg(feature = "hw-2.x")]
     #[peripheral(offset = 0x1003_0000, mask = 0x0000_7fff)] // TODO update when known
     pub ml_dsa87: MlDsa87,
 
@@ -332,6 +334,7 @@ impl CaliptraRootBus {
             key_vault: key_vault.clone(),
             sha512,
             sha256: HashSha256::new(clock),
+            #[cfg(feature = "hw-2.x")]
             ml_dsa87: MlDsa87::new(clock),
             iccm,
             dccm: Ram::new(vec![0; Self::DCCM_SIZE]),