diff --git a/library/ssl_msg.c b/library/ssl_msg.c
index fcdd024..ea1d535 100644
--- a/library/ssl_msg.c
+++ b/library/ssl_msg.c
@@ -5565,7 +5565,7 @@
                                          mbedtls_ssl_transform *transform )
 {
     ssl->transform_out = transform;
-    mbedtls_platform_zeroize( ssl->cur_out_ctr, 8 );
+    mbedtls_platform_zeroize( ssl->cur_out_ctr, sizeof( ssl->cur_out_ctr ) );
 }
 
 #if defined(MBEDTLS_SSL_PROTO_DTLS)