diff --git a/src/bip39.cpp b/src/bip39.cpp
index 2134f98dec..61c19bdbd6 100644
--- a/src/bip39.cpp
+++ b/src/bip39.cpp
@@ -147,11 +147,11 @@ bool CMnemonic::Check(SecureString mnemonic)
     return fResult;
 }
 
-// passphrase must be at most 256 characters or code may crash
+// passphrase must be at most 256 characters otherwise it would be truncated
 void CMnemonic::ToSeed(SecureString mnemonic, SecureString passphrase, SecureVector& seedRet)
 {
     SecureString ssSalt = SecureString("mnemonic") + passphrase;
-    SecureVector vchSalt(ssSalt.begin(), ssSalt.end());
+    SecureVector vchSalt(ssSalt.begin(), ssSalt.begin() + strnlen(ssSalt.data(), 256));
     seedRet.resize(64);
     PKCS5_PBKDF2_HMAC_SHA512(mnemonic.c_str(), mnemonic.size(), vchSalt.data(), vchSalt.size(), 2048, 64, seedRet.data());
 }
diff --git a/src/bip39.h b/src/bip39.h
index 9c6426b244..30f3a6880e 100644
--- a/src/bip39.h
+++ b/src/bip39.h
@@ -32,7 +32,7 @@ public:
     static SecureString Generate(int strength);    // strength in bits
     static SecureString FromData(const SecureVector& data, int len);
     static bool Check(SecureString mnemonic);
-    // passphrase must be at most 256 characters or code may crash
+    // passphrase must be at most 256 characters otherwise it would be truncated
     static void ToSeed(SecureString mnemonic, SecureString passphrase, SecureVector& seedRet);
 };