diff --git a/toxencryptsave/toxencryptsave.api.h b/toxencryptsave/toxencryptsave.api.h
index 93456235..b0e29b50 100644
--- a/toxencryptsave/toxencryptsave.api.h
+++ b/toxencryptsave/toxencryptsave.api.h
@@ -145,7 +145,7 @@ error for decryption {
  * ${pass_Key.encrypt}.
  *
  * @param plaintext A byte array of length `plaintext_len`.
- * @param plaintext_len The length of the plain text array. May be 0.
+ * @param plaintext_len The length of the plain text array. Bigger than 0.
  * @param passphrase The user-provided password.
  * @param passphrase_len The length of the password.
  * @param ciphertext The cipher text array to write the encrypted data to.
@@ -163,7 +163,7 @@ static bool pass_encrypt(const uint8_t[plaintext_len] plaintext, const uint8_t[p
  * bytes long. This delegates to ${pass_Key.decrypt}.
  *
  * @param ciphertext A byte array of length `ciphertext_len`.
- * @param ciphertext_len The length of the cipher text array. May be 0.
+ * @param ciphertext_len The length of the cipher text array. At least $PASS_ENCRYPTION_EXTRA_LENGTH.
  * @param passphrase The user-provided password.
  * @param passphrase_len The length of the password.
  * @param plaintext The plain text array to write the decrypted data to.
@@ -246,7 +246,7 @@ class pass_Key {
    * bytes long.
    *
    * @param plaintext A byte array of length `plaintext_len`.
-   * @param plaintext_len The length of the plain text array. May be 0.
+   * @param plaintext_len The length of the plain text array. Bigger than 0.
    * @param ciphertext The cipher text array to write the encrypted data to.
    *
    * @return true on success.
@@ -259,7 +259,7 @@ class pass_Key {
    * $derive or $derive_with_salt.
    *
    * @param ciphertext A byte array of length `ciphertext_len`.
-   * @param ciphertext_len The length of the cipher text array. May be 0.
+   * @param ciphertext_len The length of the cipher text array. At least $PASS_ENCRYPTION_EXTRA_LENGTH.
    * @param plaintext The plain text array to write the decrypted data to.
    *
    * @return true on success.
diff --git a/toxencryptsave/toxencryptsave.h b/toxencryptsave/toxencryptsave.h
index de53273e..d03383e9 100644
--- a/toxencryptsave/toxencryptsave.h
+++ b/toxencryptsave/toxencryptsave.h
@@ -194,7 +194,7 @@ typedef enum TOX_ERR_DECRYPTION {
  * tox_pass_key_encrypt.
  *
  * @param plaintext A byte array of length `plaintext_len`.
- * @param plaintext_len The length of the plain text array. May be 0.
+ * @param plaintext_len The length of the plain text array. Bigger than 0.
  * @param passphrase The user-provided password.
  * @param passphrase_len The length of the password.
  * @param ciphertext The cipher text array to write the encrypted data to.
@@ -211,7 +211,7 @@ bool tox_pass_encrypt(const uint8_t *plaintext, size_t plaintext_len, const uint
  * bytes long. This delegates to tox_pass_key_decrypt.
  *
  * @param ciphertext A byte array of length `ciphertext_len`.
- * @param ciphertext_len The length of the cipher text array. May be 0.
+ * @param ciphertext_len The length of the cipher text array. At least TOX_PASS_ENCRYPTION_EXTRA_LENGTH.
  * @param passphrase The user-provided password.
  * @param passphrase_len The length of the password.
  * @param plaintext The plain text array to write the decrypted data to.
@@ -298,7 +298,7 @@ bool tox_pass_key_derive_with_salt(struct Tox_Pass_Key *_key, const uint8_t *pas
  * bytes long.
  *
  * @param plaintext A byte array of length `plaintext_len`.
- * @param plaintext_len The length of the plain text array. May be 0.
+ * @param plaintext_len The length of the plain text array. Bigger than 0.
  * @param ciphertext The cipher text array to write the encrypted data to.
  *
  * @return true on success.
@@ -311,7 +311,7 @@ bool tox_pass_key_encrypt(const struct Tox_Pass_Key *_key, const uint8_t *plaint
  * tox_pass_key_derive or tox_pass_key_derive_with_salt.
  *
  * @param ciphertext A byte array of length `ciphertext_len`.
- * @param ciphertext_len The length of the cipher text array. May be 0.
+ * @param ciphertext_len The length of the cipher text array. At least TOX_PASS_ENCRYPTION_EXTRA_LENGTH.
  * @param plaintext The plain text array to write the decrypted data to.
  *
  * @return true on success.