diff --git a/include/mbedtls/ccm.h b/include/mbedtls/ccm.h
index 3dcdc9189..d50c6ec99 100644
--- a/include/mbedtls/ccm.h
+++ b/include/mbedtls/ccm.h
@@ -175,7 +175,7 @@ void mbedtls_ccm_free( mbedtls_ccm_context *ctx );
  *                  than zero, \p output must be a writable buffer of at least
  *                  that length.
  * \param tag       The buffer holding the authentication field. This must be a
- *                  readable buffer of at least \p tag_len Bytes.
+ *                  writable buffer of at least \p tag_len Bytes.
  * \param tag_len   The length of the authentication field to generate in Bytes:
  *                  4, 6, 8, 10, 12, 14 or 16.
  *
@@ -220,7 +220,7 @@ int mbedtls_ccm_encrypt_and_tag( mbedtls_ccm_context *ctx, size_t length,
  *                  than zero, \p output must be a writable buffer of at least
  *                  that length.
  * \param tag       The buffer holding the authentication field. This must be a
- *                  readable buffer of at least \p tag_len Bytes.
+ *                  writable buffer of at least \p tag_len Bytes.
  * \param tag_len   The length of the authentication field to generate in Bytes:
  *                  0, 4, 6, 8, 10, 12, 14 or 16.
  *
diff --git a/include/mbedtls/gcm.h b/include/mbedtls/gcm.h
index 4e4434ed4..1201fbd4f 100644
--- a/include/mbedtls/gcm.h
+++ b/include/mbedtls/gcm.h
@@ -182,7 +182,7 @@ int mbedtls_gcm_setkey( mbedtls_gcm_context *ctx,
  *                  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 @@ int mbedtls_gcm_update( mbedtls_gcm_context *ctx,
  *                  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.