diff --git a/ChangeLog b/ChangeLog
index 2d33641f9..233a05f85 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5,6 +5,8 @@ mbed TLS ChangeLog (Sorted per branch, date)
 Bugfix
    * Fix redundant declaration of mbedtls_ssl_list_ciphersuites. Raised by
      TrinityTonic. #1359.
+   * Fix compilation warnings with IAR toolchain, on 32 bit platform.
+     Reported by rahmanih in #683
 
 Changes
    * Support TLS testing in out-of-source builds using cmake. Fixes #1193.
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index e897ff451..14b5f2990 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -2843,7 +2843,7 @@ 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;