--- lang/cpp/src/key.h
+++ lang/cpp/src/key.h
@@ -62,6 +62,7 @@
     /* implicit */ Key(const Null &);
     Key(const shared_gpgme_key_t &key);
     Key(gpgme_key_t key, bool acquireRef);
+    Key(Key const &) = default;
 
     static const Null null;