diff --git a/src/net/addr/ether.cpp b/src/net/addr/ether.cpp
index 5266733..646637b 100644
--- a/src/net/addr/ether.cpp
+++ b/src/net/addr/ether.cpp
@@ -2,5 +2,6 @@
 
 namespace stdplus
 {
+template char* ToStr<EtherAddr>::operator()(char*, EtherAddr) const noexcept;
 template EtherAddr FromStr<EtherAddr>::operator()(std::string_view) const;
-}
+} // namespace stdplus