diff --git a/ChangeLog b/ChangeLog
index 8c82d08d1f..09afc1e110 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -13,6 +13,9 @@ Changes
    * Close a test gap in (D)TLS between the client side and the server side:
      test the handling of large packets and small packets on the client side
      in the same way as on the server side.
+   * Change the use of Windows threading to use Microsoft Visual C++ runtime
+     calls, rather than Win32 API calls directly. This is necessary to avoid
+     conflict with C runtime usage. Found and fixed by irwir.
 
 = mbed TLS 2.1.15 branch released 2018-08-31