diff --git a/ChangeLog b/ChangeLog
index 16b2f84..4ae771b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -6,6 +6,7 @@
   * Support for DTLS 1.0 and 1.2 (RFC 6347).
 
 API Changes
+   * Signature of mpi_mul_mpi() changed to make the last argument unsigned
    * Remove the PBKDF2 module (use PKCS5).
    * Remove POLARSSL_ERROR_STRERROR_BC (use mbedtls_strerror()).
    * Headers are now found in the 'mbedtls' directory (previously 'polarssl').