diff --git a/include/argparse/argparse.hpp b/include/argparse/argparse.hpp
index 5e826c5..9465827 100644
--- a/include/argparse/argparse.hpp
+++ b/include/argparse/argparse.hpp
@@ -758,6 +758,8 @@ private:
     std::stringstream stream;
     if (!m_used_name.empty()) {
       stream << m_used_name << ": ";
+    } else {
+      stream << m_names.front() << ": ";
     }
     if (m_num_args_range.is_exact()) {
       stream << m_num_args_range.get_min();
diff --git a/test/test_positional_arguments.cpp b/test/test_positional_arguments.cpp
index 0875669..cfee488 100644
--- a/test/test_positional_arguments.cpp
+++ b/test/test_positional_arguments.cpp
@@ -18,7 +18,7 @@ TEST_CASE("Missing expected positional argument" *
   argparse::ArgumentParser program("test");
   program.add_argument("input");
   REQUIRE_THROWS_WITH_AS(program.parse_args({"test"}),
-                         "1 argument(s) expected. 0 provided.",
+                         "input: 1 argument(s) expected. 0 provided.",
                          std::runtime_error);
 }