diff --git a/include/mbedtls/platform.h b/include/mbedtls/platform.h
index 768c756..490cedb 100644
--- a/include/mbedtls/platform.h
+++ b/include/mbedtls/platform.h
@@ -135,6 +135,7 @@
 
 /*
  * 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) && \