diff --git a/tests/unit/security/validation-policy-config.t.cpp b/tests/unit/security/validation-policy-config.t.cpp
index 32fbf01..83c6f52 100644
--- a/tests/unit/security/validation-policy-config.t.cpp
+++ b/tests/unit/security/validation-policy-config.t.cpp
@@ -247,7 +247,7 @@
     {
       using namespace ndn::security::transform;
       const auto& cert = this->identity.getDefaultKey().getDefaultCertificate().wireEncode();
-      bufferSource(make_span(cert.wire(), cert.size())) >> base64Encode(false) >> streamSink(os);
+      bufferSource(cert) >> base64Encode(false) >> streamSink(os);
     }
 
     this->policy.load(this->baseConfig + R"CONF(