diff --git a/ChangeLog b/ChangeLog
index 113a99dda..ca43f733b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -10,6 +10,8 @@ Bugfix
    * Fix braces in mbedtls_memory_buffer_alloc_status(). Found by sbranden, #552.
    * Fix an issue with MicroBlaze support in bn_mul.h which was causing the
      build to fail. Found by zv-io. Fixes #1651.
+   * 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;