diff --git a/src/security/v2/certificate.hpp b/src/security/v2/certificate.hpp
index c451277..c5e2c97 100644
--- a/src/security/v2/certificate.hpp
+++ b/src/security/v2/certificate.hpp
@@ -172,6 +172,9 @@
   static const name::Component KEY_COMPONENT;
 };
 
+std::ostream&
+operator<<(std::ostream& os, const Certificate& cert);
+
 /**
  * @brief Extract identity namespace from the certificate name @p certName
  */