diff --git a/include/flucoma/clients/nrt/KNNRegressorClient.hpp b/include/flucoma/clients/nrt/KNNRegressorClient.hpp
index c07201f0..57bf0255 100644
--- a/include/flucoma/clients/nrt/KNNRegressorClient.hpp
+++ b/include/flucoma/clients/nrt/KNNRegressorClient.hpp
@@ -43,8 +43,8 @@ bool check_json(const nlohmann::json& j, const KNNRegressorData&)
   return fluid::check_json(j, {"tree", "target"},
                            {JSONTypes::OBJECT, JSONTypes::OBJECT}) &&
          fluid::algorithm::check_json(j.at("tree"), algorithm::KDTree()) &&
-         fluid::check_json(j.at("labels"),
-                           FluidDataSet<std::string, std::string, 1>());
+         fluid::check_json(j.at("target"),
+                           FluidDataSet<std::string, double, 1>());
 }
 
 void from_json(const nlohmann::json& j, KNNRegressorData& data)