diff --git a/vowpalwabbit/automl.h b/vowpalwabbit/automl.h
index 95064b1d899..fa296041d31 100644
--- a/vowpalwabbit/automl.h
+++ b/vowpalwabbit/automl.h
@@ -188,8 +188,10 @@ size_t write_model_field(io_buf&, const VW::automl::interaction_config_manager&,
 }  // namespace model_utils
 }  // namespace VW
 
+namespace fmt
+{
 template <>
-struct fmt::formatter<VW::automl::automl_state> : formatter<std::string>
+struct formatter<VW::automl::automl_state> : formatter<std::string>
 {
   auto format(VW::automl::automl_state c, format_context& ctx) -> decltype(ctx.out())
   {
@@ -198,10 +200,11 @@ struct fmt::formatter<VW::automl::automl_state> : formatter<std::string>
 };
 
 template <>
-struct fmt::formatter<VW::automl::config_state> : formatter<std::string>
+struct formatter<VW::automl::config_state> : formatter<std::string>
 {
   auto format(VW::automl::config_state c, format_context& ctx) -> decltype(ctx.out())
   {
     return formatter<std::string>::format(std::string{VW::to_string(c)}, ctx);
   }
-};
\ No newline at end of file
+};
+}  // namespace fmt
\ No newline at end of file
diff --git a/vowpalwabbit/ccb_label.h b/vowpalwabbit/ccb_label.h
index aec03f14a9a..7b2b79ded8b 100644
--- a/vowpalwabbit/ccb_label.h
+++ b/vowpalwabbit/ccb_label.h
@@ -125,11 +125,14 @@ size_t write_model_field(io_buf&, const CCB::label&, const std::string&, bool);
 }  // namespace model_utils
 }  // namespace VW
 
+namespace fmt
+{
 template <>
-struct fmt::formatter<CCB::example_type> : formatter<std::string>
+struct formatter<CCB::example_type> : formatter<std::string>
 {
   auto format(CCB::example_type c, format_context& ctx) -> decltype(ctx.out())
   {
     return formatter<std::string>::format(std::string{VW::to_string(c)}, ctx);
   }
 };
+}  // namespace fmt
diff --git a/vowpalwabbit/slates_label.h b/vowpalwabbit/slates_label.h
index 84f56beacc0..4f99452eee2 100644
--- a/vowpalwabbit/slates_label.h
+++ b/vowpalwabbit/slates_label.h
@@ -72,11 +72,14 @@ size_t write_model_field(io_buf&, const VW::slates::label&, const std::string&,
 }  // namespace model_utils
 }  // namespace VW
 
+namespace fmt
+{
 template <>
-struct fmt::formatter<VW::slates::example_type> : formatter<std::string>
+struct formatter<VW::slates::example_type> : formatter<std::string>
 {
   auto format(VW::slates::example_type c, format_context& ctx) -> decltype(ctx.out())
   {
     return formatter<std::string>::format(std::string{VW::to_string(c)}, ctx);
   }
-};
\ No newline at end of file
+};
+}  // namespace fmt
\ No newline at end of file