diff --git a/lee/state_machine/core/src/program/mod.rs b/lee/state_machine/core/src/program/mod.rs
index a77d36f7b..9860030f7 100644
--- a/lee/state_machine/core/src/program/mod.rs
+++ b/lee/state_machine/core/src/program/mod.rs
@@ -53,6 +53,10 @@ impl From<AccountId> for ProgramId {
 }
 
 pub type InstructionData = Vec<u8>;
+
+/// Struct encoding the input to an LEE program. Crosses the guest boundary as
+/// `ProgramInput<InstructionData>` with the instruction still borsh-encoded.
+#[derive(BorshSerialize, BorshDeserialize)]
 pub struct ProgramInput<T> {
     pub self_program_id: ProgramId,
     pub caller_program_id: Option<ProgramId>,
@@ -60,15 +64,6 @@ pub struct ProgramInput<T> {
     pub instruction: T,
 }
 
-/// Struct encoding the input to an LEE program.
-#[derive(BorshSerialize, BorshDeserialize)]
-pub struct LeeInputHeader {
-    pub self_program_id: ProgramId,
-    pub caller_program_id: Option<ProgramId>,
-    pub pre_states: Vec<AccountWithMetadata>,
-    pub instruction_data: InstructionData,
-}
-
 /// A 32-byte seed used to compute a *Program-Derived `AccountId`* (PDA).
 ///
 /// Each program can derive up to `2^256` unique account IDs by choosing different
@@ -710,12 +705,13 @@ pub fn read_input_frame() -> Vec<u8> {
 /// Reads the LEE inputs from the guest environment.
 #[must_use]
 pub fn read_lee_inputs<T: BorshDeserialize>() -> (ProgramInput<T>, InstructionData) {
-    let LeeInputHeader {
+    let ProgramInput {
         self_program_id,
         caller_program_id,
         pre_states,
-        instruction_data,
-    } = borsh::from_slice(&read_input_frame()).expect("guest input must be a valid borsh header");
+        instruction: instruction_data,
+    } = borsh::from_slice::<ProgramInput<InstructionData>>(&read_input_frame())
+        .expect("guest input must be valid borsh");
     let instruction =
         borsh::from_slice(&instruction_data).expect("instruction must decode from borsh");
     (
diff --git a/lee/state_machine/src/program/mod.rs b/lee/state_machine/src/program/mod.rs
index 4e13c96ee..b1fd451e4 100644
--- a/lee/state_machine/src/program/mod.rs
+++ b/lee/state_machine/src/program/mod.rs
@@ -4,7 +4,7 @@ use borsh::{BorshDeserialize, BorshSerialize};
 use lee_core::{
     account::AccountWithMetadata,
     from_frame,
-    program::{InstructionData, LeeInputHeader, ProgramId, ProgramOutput},
+    program::{InstructionData, ProgramId, ProgramInput, ProgramOutput},
     to_frame,
 };
 use risc0_zkvm::{ExecutorEnv, ExecutorEnvBuilder, default_executor};
@@ -95,14 +95,14 @@ impl Program {
         instruction_data: &[u8],
         env_builder: &mut ExecutorEnvBuilder,
     ) -> Result<(), LeeError> {
-        let header = LeeInputHeader {
+        let input = ProgramInput {
             self_program_id: self.id,
             caller_program_id,
             pre_states: pre_states.to_vec(),
-            instruction_data: instruction_data.to_vec(),
+            instruction: instruction_data.to_vec(),
         };
         let payload =
-            borsh::to_vec(&header).map_err(|e| LeeError::ProgramWriteInputFailed(e.to_string()))?;
+            borsh::to_vec(&input).map_err(|e| LeeError::ProgramWriteInputFailed(e.to_string()))?;
         env_builder.write_slice(&to_frame(&payload));
         Ok(())
     }