diff --git a/include/mbedtls/gcm.h b/include/mbedtls/gcm.h
index 4e4434e..1201fbd 100644
--- a/include/mbedtls/gcm.h
+++ b/include/mbedtls/gcm.h
@@ -182,7 +182,7 @@
  *                  than zero, this must be a writable buffer of at least that
  *                  size in Bytes.
  * \param tag_len   The length of the tag to generate.
- * \param tag       The buffer for holding the tag. This must be a readable
+ * \param tag       The buffer for holding the tag. This must be a writable
  *                  buffer of at least \p tag_len Bytes.
  *
  * \return          \c 0 if the encryption or decryption was performed
@@ -310,7 +310,7 @@
  *                  tag. The tag can have a maximum length of 16 Bytes.
  *
  * \param ctx       The GCM context. This must be initialized.
- * \param tag       The buffer for holding the tag. This must be a readable
+ * \param tag       The buffer for holding the tag. This must be a writable
  *                  buffer of at least \p tag_len Bytes.
  * \param tag_len   The length of the tag to generate. This must be at least
  *                  four.