diff --git a/plotjuggler_plugins/ParserROS/ros_parser.cpp b/plotjuggler_plugins/ParserROS/ros_parser.cpp
index 124fda319..2e5a61629 100644
--- a/plotjuggler_plugins/ParserROS/ros_parser.cpp
+++ b/plotjuggler_plugins/ParserROS/ros_parser.cpp
@@ -22,7 +22,9 @@ ParserROS::ParserROS(const std::string& topic_name, const std::string& type_name
       clampLargeArray() ? Parser::KEEP_LARGE_ARRAYS : Parser::DISCARD_LARGE_ARRAYS;
 
   _parser.setMaxArrayPolicy(policy, maxArraySize());
-  _has_header = _parser.getSchema()->root_msg->field(0).type().baseName() == "std_msgs/Header";
+
+  const auto& root_fields = _parser.getSchema()->root_msg->fields();
+  _has_header = !root_fields.empty() && root_fields.front().type().baseName() == "std_msgs/Header";
 
   using std::placeholders::_1;
   using std::placeholders::_2;
diff --git a/plotjuggler_plugins/ParserROS/ros_parser.h b/plotjuggler_plugins/ParserROS/ros_parser.h
index 5eada987d..992b28aee 100644
--- a/plotjuggler_plugins/ParserROS/ros_parser.h
+++ b/plotjuggler_plugins/ParserROS/ros_parser.h
@@ -19,7 +19,7 @@ class ParserROS : public PJ::MessageParser
 
 protected:
   RosMsgParser::Parser _parser;
-  std::shared_ptr<RosMsgParser::Deserializer> _deserializer;
+  std::unique_ptr<RosMsgParser::Deserializer> _deserializer;
   RosMsgParser::FlatMessage _flat_msg;
   std::string _topic;