diff --git a/include/mbedtls/x509_crt.h b/include/mbedtls/x509_crt.h
index e6a9f7a..3d64a4c 100644
--- a/include/mbedtls/x509_crt.h
+++ b/include/mbedtls/x509_crt.h
@@ -156,6 +156,10 @@
  * Security profile for certificate verification.
  *
  * All lists are bitfields, built by ORing flags from MBEDTLS_X509_ID_FLAG().
+ *
+ * The fields of this structure are part of the public API and can be
+ * manipulated directly by applications. Future versions of the library may
+ * add extra fields or reorder existing fields.
  */
 typedef struct mbedtls_x509_crt_profile
 {