diff --git a/src/net/addr/subnet.cpp b/src/net/addr/subnet.cpp
index 36d6049..d7cb24f 100644
--- a/src/net/addr/subnet.cpp
+++ b/src/net/addr/subnet.cpp
@@ -15,4 +15,9 @@
 template class Subnet46<In4Addr, uint8_t>;
 template class Subnet46<In6Addr, uint8_t>;
 
+template char* SubnetToStr<Subnet4>::operator()(char*, Subnet4) const noexcept;
+template char* SubnetToStr<Subnet6>::operator()(char*, Subnet6) const noexcept;
+template char* SubnetToStr<SubnetAny>::operator()(char*,
+                                                  SubnetAny) const noexcept;
+
 } // namespace stdplus::detail