diff --git a/ChangeLog b/ChangeLog
index 93d017c6c6..838238b15c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,7 +3,8 @@ mbed TLS ChangeLog (Sorted per branch, date)
 = mbed TLS x.x.x branch released xxxx-xx-xx
 
 Bugfix
-
+   * Fix compilation warnings with IAR toolchain, on 32 bit platform.
+     Reported by rahmanih in #683
    * Fix braces in mbedtls_memory_buffer_alloc_status(). Found by sbranden, #552.
    * Added the macro MBEDTLS_X509_MAX_FILE_PATH_LEN that enables the user to
      configure the maximum length of a file path that can be buffered when
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index af3722cec2..9a884f055e 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -2686,7 +2686,7 @@ static int ssl_write_server_key_exchange( mbedtls_ssl_context *ssl )
 
 #if defined(MBEDTLS_KEY_EXCHANGE__SOME_PFS__ENABLED)
     unsigned char *p = ssl->out_msg + 4;
-    size_t len;
+    size_t len = 0;
 #if defined(MBEDTLS_KEY_EXCHANGE__WITH_SERVER_SIGNATURE__ENABLED)
     unsigned char *dig_signed = p;
     size_t dig_signed_len = 0;