diff --git a/ChangeLog.d/fix-tls-padbuf-zeroization b/ChangeLog.d/fix-tls-padbuf-zeroization
new file mode 100644
index 000000000..36451cb4b
--- /dev/null
+++ b/ChangeLog.d/fix-tls-padbuf-zeroization
@@ -0,0 +1,4 @@
+Security
+   * Fix a case where potentially sensitive information held in memory would not
+     be completely zeroized during TLS 1.2 handshake, in both server and client
+     configurations.
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 6ed8a863e..7a1f85531 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -7722,7 +7722,7 @@ static int ssl_calc_finished_tls_generic(mbedtls_ssl_context *ssl, void *ctx,
 
     MBEDTLS_SSL_DEBUG_BUF(3, "calc finished result", buf, len);
 
-    mbedtls_platform_zeroize(padbuf, sizeof(padbuf));
+    mbedtls_platform_zeroize(padbuf, hlen);
 
     MBEDTLS_SSL_DEBUG_MSG(2, ("<= calc finished"));