diff --git a/src/io/tree.cpp b/src/io/tree.cpp
index 7928a86d9ef1..3ca6f7bdb5c0 100644
--- a/src/io/tree.cpp
+++ b/src/io/tree.cpp
@@ -415,16 +415,20 @@ std::string Tree::ToJSON() const {
   str_buf << "\"num_leaves\":" << num_leaves_ << "," << '\n';
   str_buf << "\"num_cat\":" << num_cat_ << "," << '\n';
   str_buf << "\"shrinkage\":" << shrinkage_ << "," << '\n';
-  // if (num_leaves_ == 1) {
-  //   if (is_linear_) {
-  //     str_buf << "\"tree_structure\":{" << "\"leaf_value\":" << leaf_value_[0] << ", " << "\n";
-  //     str_buf << LinearModelToJSON(0) << "}" << "\n";
-  //   } else {
-  //     str_buf << "\"tree_structure\":{" << "\"leaf_value\":" << leaf_value_[0] << "}" << '\n';
-  //   }
-  // } else {
-  str_buf << "\"tree_structure\":" << NodeToJSON(0) << '\n';
-  // }
+  if (num_leaves_ == 1) {
+    str_buf << "\"tree_structure\":{";
+    if (is_linear_) {
+      str_buf << "\"leaf_value\":" << leaf_value_[0] << ", " << '\n';
+      str_buf << "\"leaf_count\":" << leaf_count_[0] << ", " << '\n';
+      str_buf << LinearModelToJSON(0);
+    } else {
+      str_buf << "\"leaf_value\":" << leaf_value_[0] << ", " << '\n';
+      str_buf << "\"leaf_count\":" << leaf_count_[0];
+    }
+    str_buf << "}" << '\n';
+  } else {
+    str_buf << "\"tree_structure\":" << NodeToJSON(0) << '\n';
+  }
   return str_buf.str();
 }