diff --git a/include/argparse.hpp b/include/argparse.hpp
index 4ac2468..faf1d74 100644
--- a/include/argparse.hpp
+++ b/include/argparse.hpp
@@ -1919,6 +1919,12 @@ namespace argparse
                         }
                         else
                         {
+                            if (m_options.mutually_exclusive_group != nullptr
+                                && m_options.required)
+                            {
+                                throw option_error("mutually exclusive arguments must be optional");
+                            }
+
                             m_arguments.emplace_back(OptionalArgument(std::move(m_options)));
                         }
                     }
diff --git a/test/unittest/test_argument_parser.cpp b/test/unittest/test_argument_parser.cpp
index e8a9062..edce5c4 100644
--- a/test/unittest/test_argument_parser.cpp
+++ b/test/unittest/test_argument_parser.cpp
@@ -375,6 +375,14 @@ TEST_CASE("Adding an optional argument to a mutually exclusive group does not re
     CHECK_NOTHROW(group.add_argument("-o"));
 }
 
+TEST_CASE("Adding a required optional argument to a mutually exclusive group results in error")
+{
+    auto parser = argparse::ArgumentParser();
+    auto group = parser.add_mutually_exclusive_group();
+
+    CHECK_THROWS_WITH_AS(group.add_argument("-o").required(true), "mutually exclusive arguments must be optional", argparse::option_error);
+}
+
 TEST_CASE("Test combining Handle values")
 {
     CHECK((argparse::Handle::none | argparse::Handle::errors) == argparse::Handle::errors);