diff --git a/esphome/components/api/user_services.h b/esphome/components/api/user_services.h
index dba2d055bf..3996c921a9 100644
--- a/esphome/components/api/user_services.h
+++ b/esphome/components/api/user_services.h
@@ -35,7 +35,7 @@ template<typename... Ts> class UserServiceBase : public UserServiceDescriptor {
     msg.set_name(StringRef(this->name_));
     msg.key = this->key_;
     std::array<enums::ServiceArgType, sizeof...(Ts)> arg_types = {to_service_arg_type<Ts>()...};
-    for (int i = 0; i < sizeof...(Ts); i++) {
+    for (size_t i = 0; i < sizeof...(Ts); i++) {
       msg.args.emplace_back();
       auto &arg = msg.args.back();
       arg.type = arg_types[i];