diff --git a/include/mbedtls/mbedtls_config.h b/include/mbedtls/mbedtls_config.h
index e15104216..bb2d66deb 100644
--- a/include/mbedtls/mbedtls_config.h
+++ b/include/mbedtls/mbedtls_config.h
@@ -3680,7 +3680,7 @@
 
 /* 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_SETBUF      setbuf /**< Default setbuf to use, can be undefined */
 //#define MBEDTLS_PLATFORM_STD_EXIT            exit /**< Default exit to use, can be undefined */
diff --git a/include/mbedtls/platform.h b/include/mbedtls/platform.h
index 768c756b9..490cedb4a 100644
--- a/include/mbedtls/platform.h
+++ b/include/mbedtls/platform.h
@@ -135,6 +135,7 @@ 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) && \