diff --git a/README.md b/README.md
index 32ab827..d70fc5b 100644
--- a/README.md
+++ b/README.md
@@ -15,8 +15,8 @@ This Anchor program enables users to migrate their tokens from an old token mint
 
 - Node.js and Yarn
 - Rust and Cargo
-- Solana CLI tools
-- Anchor CLI
+- Solana CLI (v2.3.0) tools
+- Anchor CLI (v0.31.1)
 
 ### Installation
 
diff --git a/programs/token-migrator/src/contexts/initialize.rs b/programs/token-migrator/src/contexts/initialize.rs
index e187df3..831e6fa 100644
--- a/programs/token-migrator/src/contexts/initialize.rs
+++ b/programs/token-migrator/src/contexts/initialize.rs
@@ -6,11 +6,7 @@ use crate::state::{Strategy, Vault};
 #[derive(Accounts)]
 #[instruction(mint_from: Pubkey, mint_to: Pubkey)]
 pub struct Initialize<'info> {
-    #[account(
-        mut,
-        // ℹ️ NOTE: Remove `address` constraint to make contract permissionless.
-        address = pubkey!("ELT1uRmtFvYP6WSrc4mCZaW7VVbcdkcKAj39aHSVCmwH")
-    )]
+    #[account(mut)]
     admin: Signer<'info>,
 
     // Ensure our vaults were initialized in preInstructions
@@ -45,6 +41,8 @@ impl<'info> Initialize<'info> {
         strategy: Strategy,
         bump: [u8; 1],
     ) -> Result<()> {
+        strategy.validate()?;
+
         self.vault.set_inner(Vault {
             admin: self.admin.key(),
             mint_from,
diff --git a/programs/token-migrator/src/contexts/migrate.rs b/programs/token-migrator/src/contexts/migrate.rs
index f627f15..8c4d09b 100644
--- a/programs/token-migrator/src/contexts/migrate.rs
+++ b/programs/token-migrator/src/contexts/migrate.rs
@@ -125,7 +125,7 @@ impl<'info> Migrate<'info> {
     /// # Supply From
     ///
     /// Calculates supply of `from` token to simulate a token burn. This is calculated by:
-    /// ```
+    /// ```ignore
     /// let supply_from = mint_from.supply - vault_from_ata.amount
     /// ```
     #[inline(always)]
diff --git a/programs/token-migrator/src/errors.rs b/programs/token-migrator/src/errors.rs
new file mode 100644
index 0000000..f6f8aa7
--- /dev/null
+++ b/programs/token-migrator/src/errors.rs
@@ -0,0 +1,7 @@
+use anchor_lang::prelude::*;
+
+#[error_code]
+pub enum MigratorError {
+    #[msg("Fixed strategy exponent out of range (|e| must be <= 19)")]
+    ExponentOutOfRange,
+}
diff --git a/programs/token-migrator/src/lib.rs b/programs/token-migrator/src/lib.rs
index ab0b0c3..f4bea0b 100644
--- a/programs/token-migrator/src/lib.rs
+++ b/programs/token-migrator/src/lib.rs
@@ -9,6 +9,8 @@ pub use state::*;
 
 pub mod events;
 
+pub mod errors;
+
 #[cfg(not(feature = "no-entrypoint"))]
 use solana_security_txt::security_txt;
 
diff --git a/programs/token-migrator/src/state.rs b/programs/token-migrator/src/state.rs
index 4a5baf2..755d244 100644
--- a/programs/token-migrator/src/state.rs
+++ b/programs/token-migrator/src/state.rs
@@ -1,5 +1,7 @@
 use anchor_lang::prelude::*;
 
+use crate::errors::MigratorError;
+
 #[derive(AnchorSerialize, AnchorDeserialize, Clone, Copy, PartialEq, Eq, InitSpace)]
 /// # Strategy
 ///
@@ -12,7 +14,30 @@ pub enum Strategy {
     Fixed { e: i8 },
 }
 
+/// Maximum magnitude of the `Fixed` exponent. `10^19` is the largest power of
+/// ten that fits in a `u64` (`10^20` overflows), so bounding `|e| <= 19` keeps
+/// the `10u64.pow(|e|)` scaling in `withdraw_amount` from overflowing and rules
+/// out the `i8::MIN` negation panic.
+pub const MAX_FIXED_EXPONENT: u8 = 19;
+
 impl Strategy {
+    /// # Validate
+    /// Ensures the strategy parameters are within safe bounds before the vault
+    /// is persisted. For `Fixed`, the exponent magnitude must be
+    /// `<= MAX_FIXED_EXPONENT` so the `10u64.pow(|e|)` scaling in
+    /// `withdraw_amount` cannot overflow. `ProRata` carries no parameters and is
+    /// always valid.
+    pub fn validate(&self) -> Result<()> {
+        if let Strategy::Fixed { e } = self {
+            require!(
+                e.unsigned_abs() <= MAX_FIXED_EXPONENT,
+                MigratorError::ExponentOutOfRange
+            );
+        }
+
+        Ok(())
+    }
+
     /// # Withdraw Amount
     /// Calculates the amount of tokens the user can withdraw based upon the `Strategy` implemented.
     #[inline(always)]
@@ -94,4 +119,24 @@ mod tests {
         let strategy = Strategy::ProRata;
         assert_eq!(strategy.withdraw_amount(10, 100, 100).unwrap(), 10);
     }
+
+    #[test]
+    fn test_validate_pro_rata_ok() {
+        assert!(Strategy::ProRata.validate().is_ok());
+    }
+
+    #[test]
+    fn test_validate_fixed_within_bounds_ok() {
+        assert!(Strategy::Fixed { e: 0 }.validate().is_ok());
+        assert!(Strategy::Fixed { e: 19 }.validate().is_ok());
+        assert!(Strategy::Fixed { e: -19 }.validate().is_ok());
+    }
+
+    #[test]
+    fn test_validate_fixed_out_of_bounds_err() {
+        assert!(Strategy::Fixed { e: 20 }.validate().is_err());
+        assert!(Strategy::Fixed { e: -20 }.validate().is_err());
+        assert!(Strategy::Fixed { e: i8::MAX }.validate().is_err());
+        assert!(Strategy::Fixed { e: i8::MIN }.validate().is_err());
+    }
 }