diff --git a/src/learner.cc b/src/learner.cc
index db3a88f16514..7b55cc3799c5 100644
--- a/src/learner.cc
+++ b/src/learner.cc
@@ -214,8 +214,6 @@ struct LearnerModelParamLegacy : public dmlc::Parameter<LearnerModelParamLegacy>
     pos += 1;
     std::memcpy(data.data() + pos, &num_class, sizeof(num_class));
     pos += 1;
-    std::memcpy(data.data() + pos, &num_target, sizeof(num_target));
-    pos += 1;
     std::memcpy(data.data() + pos, &major_version, sizeof(major_version));
     pos += 1;
     std::memcpy(data.data() + pos, &minor_version, sizeof(minor_version));