diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 1381c1fd1..d9835b31d 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -3798,7 +3798,7 @@
 
 /* Platform options */
 //#define MBEDTLS_PLATFORM_STD_MEM_HDR   <stdlib.h> /**< Header to include if MBEDTLS_PLATFORM_NO_STD_FUNCTIONS is defined. Don't define if no header is needed. */
-//#define MBEDTLS_PLATFORM_STD_CALLOC        calloc /**< Default allocator to use, can be undefined */
+//#define MBEDTLS_PLATFORM_STD_CALLOC        calloc /**< Default allocator to use, can be undefined. Please note that it should zeroize the buffer after allocation. */
 //#define MBEDTLS_PLATFORM_STD_FREE            free /**< Default free to use, can be undefined */
 //#define MBEDTLS_PLATFORM_STD_EXIT            exit /**< Default exit to use, can be undefined */
 //#define MBEDTLS_PLATFORM_STD_TIME            time /**< Default time to use, can be undefined. MBEDTLS_HAVE_TIME must be enabled */
diff --git a/include/mbedtls/platform.h b/include/mbedtls/platform.h
index 9033852be..121ba3ad7 100644
--- a/include/mbedtls/platform.h
+++ b/include/mbedtls/platform.h
@@ -140,6 +140,7 @@ extern "C" {
 
 /*
  * The function pointers for calloc and free.
+ * mbedtls_calloc will allocate and zeroize the buffer.
  */
 #if defined(MBEDTLS_PLATFORM_MEMORY)
 #if defined(MBEDTLS_PLATFORM_FREE_MACRO) && \