diff --git a/p-token/src/entrypoint-runtime-verification.rs b/p-token/src/entrypoint-runtime-verification.rs
index ecec8b39..fdea239a 100644
--- a/p-token/src/entrypoint-runtime-verification.rs
+++ b/p-token/src/entrypoint-runtime-verification.rs
@@ -652,6 +652,11 @@ fn inner_process_remaining_instruction(
 #[no_mangle]
 pub unsafe extern "C" fn use_tests(acc: &AccountInfo) {
     test_ptoken_domain_data(acc, acc, acc);
+    let _ =
+        test_validate_owner(unsafe { &*(acc as *const AccountInfo as *const [AccountInfo; 2]) });
+    let _ = test_validate_owner_multisig(unsafe {
+        &*(acc as *const AccountInfo as *const [AccountInfo; 5])
+    });
 }
 
 // special test for basic domain data access
@@ -742,6 +747,8 @@ include!("../../specs/shared/test_process_transfer.rs");
 include!("../../specs/shared/test_process_transfer_multisig.rs");
 include!("../../specs/shared/test_process_amount_to_ui_amount.rs");
 include!("../../specs/shared/test_process_ui_amount_to_amount.rs");
+include!("../../specs/shared/test_validate_owner.rs");
+include!("../../specs/shared/test_validate_owner_multisig.rs");
 
 // Withdraw Excess Lamports test harnesses (p-token specific)
 include!("../../specs/withdraw-p-token.rs");
diff --git a/p-token/test-properties/proofs.md b/p-token/test-properties/proofs.md
index 3ac6deda..883222cc 100644
--- a/p-token/test-properties/proofs.md
+++ b/p-token/test-properties/proofs.md
@@ -3,6 +3,8 @@ Proofs to run with `run-proofs.sh -a`:
 | Start symbol name                              |
 |------------------------------------------------|
 | test_ptoken_domain_data                        |
+| test_validate_owner                            |
+| test_validate_owner_multisig                   |
 | test_process_approve                           |
 | test_process_approve_checked                   |
 | test_process_withdraw_excess_lamports_account  |
diff --git a/specs/shared/inner_test_validate_owner.rs b/specs/shared/inner_test_validate_owner.rs
index 5f25fdf4..2abd0abd 100644
--- a/specs/shared/inner_test_validate_owner.rs
+++ b/specs/shared/inner_test_validate_owner.rs
@@ -1,3 +1,65 @@
+/// Computes the expected result of mod.rs::validate_owner.
+#[inline(never)]
+fn expected_validate_owner_result(
+    expected_owner: &Pubkey,
+    owner_account_info: &AccountInfo,
+    tx_signers: &[AccountInfo],
+    maybe_multisig_is_initialised: Option<Result<bool, ProgramError>>,
+) -> Result<(), ProgramError> {
+    if expected_owner != key!(owner_account_info) {
+        return Err(ProgramError::Custom(4));
+    }
+    // We add the `maybe_multisig_is_initialised.is_some()` to not branch vacuously in the
+    // non-multisig cases
+    else if maybe_multisig_is_initialised.is_some()
+        && owner_account_info.data_len() == Multisig::LEN
+        && (owner!(owner_account_info) == &PROGRAM_ID)
+    {
+        // Guaranteed to succeed by `cheatcode_is_multisig`
+        let multisig_is_initialised = maybe_multisig_is_initialised.unwrap();
+        if multisig_is_initialised.is_err() {
+            return Err(ProgramError::InvalidAccountData);
+        } else if !multisig_is_initialised.unwrap() {
+            return Err(ProgramError::UninitializedAccount);
+        } else {
+            let multisig = get_multisig(owner_account_info);
+
+            // Did all declared and allowd signers sign?
+            let unsigned_exists = tx_signers.iter().any(|potential_signer| {
+                multisig.signers.iter().any(|registered_key| {
+                    registered_key == key!(potential_signer) && !is_signer!(potential_signer)
+                })
+            });
+            if unsigned_exists {
+                return Err(ProgramError::MissingRequiredSignature);
+            }
+
+            // Were enough signatures received?
+            let signers_count = multisig.signers
+                .iter()
+                .filter_map(|registered_key| {
+                    tx_signers.iter().find(|potential_signer| {
+                        key!(potential_signer) == registered_key && is_signer!(potential_signer)
+                    })
+                })
+                .count();
+
+            // Check if we have enough signers
+            if signers_count < multisig.m as usize {
+                return Err(ProgramError::MissingRequiredSignature);
+            }
+
+            return Ok(());
+        }
+    }
+    // Non-multisig case - check if owner_account_info.is_signer()
+    else if !is_signer!(owner_account_info) {
+        return Err(ProgramError::MissingRequiredSignature);
+    }
+
+    Ok(())
+}
+
 /// This function encapsulates the specification of validating the signature
 /// requirements In particular, code from mod.rs::validate_owner is checked
 #[inline(never)]
diff --git a/specs/shared/test_validate_owner.rs b/specs/shared/test_validate_owner.rs
new file mode 100644
index 00000000..c6fcdb4f
--- /dev/null
+++ b/specs/shared/test_validate_owner.rs
@@ -0,0 +1,33 @@
+/// accounts[0]    // Source Account Info (provides expected_owner)
+/// accounts[1]    // Owner Info
+#[inline(never)]
+fn test_validate_owner(
+    accounts: &[AccountInfo; 2],
+) -> ProgramResult {
+    cheatcode_account!(&accounts[0]);    // Source Account
+    cheatcode_account!(&accounts[1]);    // Owner
+
+    //-Initial State-----------------------------------------------------------
+    let src_old = get_account(&accounts[0]);
+    let expected_owner = src_old.owner;
+    let maybe_multisig_is_initialised = None;
+
+    //-Process Instruction-----------------------------------------------------
+    let result = expected_validate_owner_result(
+        &expected_owner,
+        &accounts[1],
+        &accounts[2..],
+        maybe_multisig_is_initialised.clone(),
+    );
+
+    //-Assert Postconditions---------------------------------------------------
+    inner_test_validate_owner(
+        &expected_owner,
+        &accounts[1],
+        &accounts[2..],
+        maybe_multisig_is_initialised,
+        result.clone(),
+    )?;
+
+    result
+}
diff --git a/specs/shared/test_validate_owner_multisig.rs b/specs/shared/test_validate_owner_multisig.rs
new file mode 100644
index 00000000..0526d482
--- /dev/null
+++ b/specs/shared/test_validate_owner_multisig.rs
@@ -0,0 +1,34 @@
+/// accounts[0]    // Source Account Info (provides expected_owner)
+/// accounts[1]    // Owner Info (multisig)
+/// accounts[2..4] // Signers
+#[inline(never)]
+fn test_validate_owner_multisig(
+    accounts: &[AccountInfo; 5],
+) -> ProgramResult {
+    cheatcode_account!(&accounts[0]);    // Source Account
+    cheatcode_multisig!(&accounts[1]);   // Owner (multisig)
+
+    //-Initial State-----------------------------------------------------------
+    let src_old = get_account(&accounts[0]);
+    let expected_owner = src_old.owner;
+    let maybe_multisig_is_initialised = Some(get_multisig(&accounts[1]).is_initialized());
+
+    //-Process Instruction-----------------------------------------------------
+    let result = expected_validate_owner_result(
+        &expected_owner,
+        &accounts[1],
+        &accounts[2..],
+        maybe_multisig_is_initialised.clone(),
+    );
+
+    //-Assert Postconditions---------------------------------------------------
+    inner_test_validate_owner(
+        &expected_owner,
+        &accounts[1],
+        &accounts[2..],
+        maybe_multisig_is_initialised,
+        result.clone(),
+    )?;
+
+    result
+}