diff --git a/tests/unit/face.t.cpp b/tests/unit/face.t.cpp
index c4ae026..f369d6f 100644
--- a/tests/unit/face.t.cpp
+++ b/tests/unit/face.t.cpp
@@ -44,7 +44,7 @@
     : face(m_io, m_keyChain, {true, !std::is_same_v<PrefixRegReply, NoPrefixRegReply>})
   {
     static_assert(std::is_same_v<PrefixRegReply, WantPrefixRegReply> ||
-                  std::is_same_v<PrefixRegReply, NoPrefixRegReply>, "");
+                  std::is_same_v<PrefixRegReply, NoPrefixRegReply>);
   }
 
   /** \brief Execute a prefix registration, and optionally check the name in callback.