diff --git a/src/verify.rs b/src/verify.rs
index 96852e3..6e2b5a6 100644
--- a/src/verify.rs
+++ b/src/verify.rs
@@ -3,7 +3,7 @@
 //! This module provides functions to verify that a puzzle's private key
 //! correctly derives its stored address across multiple blockchains.
 
-use crate::{Chain, PubkeyFormat, Puzzle};
+use crate::{Chain, Passphrase, PubkeyFormat, Puzzle};
 use k256::ecdsa::SigningKey;
 use k256::elliptic_curve::sec1::ToEncodedPoint;
 use k256::PublicKey;
@@ -105,7 +105,16 @@ pub fn verify_puzzle(puzzle: &Puzzle) -> Result<VerifyResult, VerifyError> {
         let path = seed.path.ok_or_else(|| {
             VerifyError::UnverifiableKey("Seed has no derivation path".to_string())
         })?;
-        verify_seed(phrase, path, expected_address, pubkey_format)?
+        let passphrase = match seed.entropy.as_ref().and_then(|e| e.passphrase) {
+            Some(Passphrase::Required) => {
+                return Err(VerifyError::UnverifiableKey(
+                    "Seed requires unknown passphrase".to_string(),
+                ))
+            }
+            Some(Passphrase::Known(p)) => p,
+            None => "",
+        };
+        verify_seed(phrase, path, expected_address, pubkey_format, passphrase)?
     } else {
         return Err(VerifyError::NoPrivateKey);
     };
@@ -502,6 +511,7 @@ pub fn verify_seed(
     path: &str,
     expected_address: &str,
     pubkey_format: PubkeyFormat,
+    passphrase: &str,
 ) -> Result<(String, String), VerifyError> {
     use bip32::{DerivationPath, XPrv};
     use bip39::Mnemonic;
@@ -510,7 +520,7 @@ pub fn verify_seed(
     let mnemonic = Mnemonic::parse_normalized(phrase)
         .map_err(|e| VerifyError::InvalidKey(format!("Invalid mnemonic: {}", e)))?;
 
-    let seed = mnemonic.to_seed("");
+    let seed = mnemonic.to_seed(passphrase);
 
     let derivation_path = DerivationPath::from_str(path)
         .map_err(|e| VerifyError::InvalidKey(format!("Invalid derivation path: {}", e)))?;
diff --git a/tests/cli.rs b/tests/cli.rs
index 3d36594..060d1ba 100644
--- a/tests/cli.rs
+++ b/tests/cli.rs
@@ -1098,7 +1098,7 @@ mod verify_seed {
         let path = "m/44'/0'/0'/0/0";
         let expected = "1LqBGSKuX5yYUonjxT5qGfpUsXKYYWeabA";
 
-        let result = verify_seed(phrase, path, expected, PubkeyFormat::Compressed);
+        let result = verify_seed(phrase, path, expected, PubkeyFormat::Compressed, "");
         assert!(
             result.is_ok(),
             "Seed verification should succeed: {:?}",
@@ -1115,7 +1115,7 @@ mod verify_seed {
         let path = "m/84'/0'/0'/0/0";
         let expected = "bc1qcr8te4kr609gcawutmrza0j4xv80jy8z306fyu";
 
-        let result = verify_seed(phrase, path, expected, PubkeyFormat::Compressed);
+        let result = verify_seed(phrase, path, expected, PubkeyFormat::Compressed, "");
         assert!(
             result.is_ok(),
             "Seed verification with SegWit path should succeed: {:?}",
@@ -1125,13 +1125,46 @@ mod verify_seed {
         assert_eq!(derived, expected);
     }
 
+    #[test]
+    fn verify_seed_with_passphrase() {
+        // BIP39 test vector with passphrase "TREZOR"
+        // Same mnemonic but passphrase changes the derived seed entirely
+        let phrase = "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about";
+        let path = "m/44'/0'/0'/0/0";
+
+        // Verify passphrase produces a different address than empty passphrase
+        let no_pass = "1LqBGSKuX5yYUonjxT5qGfpUsXKYYWeabA";
+        let result = verify_seed(phrase, path, no_pass, PubkeyFormat::Compressed, "TREZOR");
+        assert!(
+            result.is_err(),
+            "TREZOR passphrase should derive a different address than empty passphrase"
+        );
+    }
+
+    #[test]
+    fn verify_seed_with_passphrase_derives_correct_address() {
+        // BIP39 "abandon...about" with passphrase "TREZOR" at m/44'/0'/0'/0/0
+        let phrase = "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about";
+        let path = "m/44'/0'/0'/0/0";
+        let expected = "1PEha8dk5Me5J1rZWpgqSt5F4BroTBLS5y";
+
+        let result = verify_seed(phrase, path, expected, PubkeyFormat::Compressed, "TREZOR");
+        assert!(
+            result.is_ok(),
+            "Should verify correctly with TREZOR passphrase: {:?}",
+            result
+        );
+        let (derived, _hex) = result.unwrap();
+        assert_eq!(derived, expected);
+    }
+
     #[test]
     fn verify_seed_invalid_phrase() {
         let phrase = "invalid mnemonic phrase that is not valid";
         let path = "m/44'/0'/0'/0/0";
         let expected = "1LqBGSKuX5yYUonjxT5qGfpUsXKYYWeabA";
 
-        let result = verify_seed(phrase, path, expected, PubkeyFormat::Compressed);
+        let result = verify_seed(phrase, path, expected, PubkeyFormat::Compressed, "");
         assert!(result.is_err(), "Should fail with invalid mnemonic");
     }
 
@@ -1141,7 +1174,7 @@ mod verify_seed {
         let path = "invalid/path/format";
         let expected = "1LqBGSKuX5yYUonjxT5qGfpUsXKYYWeabA";
 
-        let result = verify_seed(phrase, path, expected, PubkeyFormat::Compressed);
+        let result = verify_seed(phrase, path, expected, PubkeyFormat::Compressed, "");
         assert!(result.is_err(), "Should fail with invalid derivation path");
     }
 }