diff --git a/src/openvpn/crypto_openssl.c b/src/openvpn/crypto_openssl.c
index e6abd8f..e6873bb 100644
--- a/src/openvpn/crypto_openssl.c
+++ b/src/openvpn/crypto_openssl.c
@@ -528,7 +528,7 @@
 cleanup:
     OPENSSL_free(name_read);
     OPENSSL_free(header_read);
-    OPENSSL_free(data_read);
+    OPENSSL_clear_free(data_read, data_read_len);
     if (!BIO_free(bio))
     {
         ret = false;