diff --git a/test/argparse_details.cppm b/test/argparse_details.cppm
new file mode 100644
index 0000000..1c1668d
--- /dev/null
+++ b/test/argparse_details.cppm
@@ -0,0 +1,10 @@
+module;
+
+#include <argparse/argparse.hpp>
+
+export module argparse.details;
+
+export namespace argparse::details {
+    using argparse::details::repr;
+}
+
diff --git a/test/test_actions.cpp b/test/test_actions.cpp
index 07f59c9..aa8cd3d 100644
--- a/test/test_actions.cpp
+++ b/test/test_actions.cpp
@@ -1,4 +1,8 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 
 using doctest::test_suite;
diff --git a/test/test_append.cpp b/test/test_append.cpp
index 4934514..0114f71 100644
--- a/test/test_append.cpp
+++ b/test/test_append.cpp
@@ -1,6 +1,13 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 
+#include <vector>
+#include <string>
+
 using doctest::test_suite;
 
 TEST_CASE("Simplest .append" * test_suite("append")) {
diff --git a/test/test_as_container.cpp b/test/test_as_container.cpp
index 2f795fb..fb6e87c 100644
--- a/test/test_as_container.cpp
+++ b/test/test_as_container.cpp
@@ -1,4 +1,8 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 
 using doctest::test_suite;
diff --git a/test/test_bool_operator.cpp b/test/test_bool_operator.cpp
index 93a3be2..aada150 100644
--- a/test/test_bool_operator.cpp
+++ b/test/test_bool_operator.cpp
@@ -1,4 +1,9 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
+
 #include <doctest.hpp>
 
 using doctest::test_suite;
diff --git a/test/test_compound_arguments.cpp b/test/test_compound_arguments.cpp
index 3bc1601..fc25fdc 100644
--- a/test/test_compound_arguments.cpp
+++ b/test/test_compound_arguments.cpp
@@ -1,4 +1,8 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 #include <test_utility.hpp>
 
diff --git a/test/test_const_correct.cpp b/test/test_const_correct.cpp
index 1acfdd4..a139679 100644
--- a/test/test_const_correct.cpp
+++ b/test/test_const_correct.cpp
@@ -1,4 +1,8 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 
 using doctest::test_suite;
diff --git a/test/test_container_arguments.cpp b/test/test_container_arguments.cpp
index 5eab026..e659695 100644
--- a/test/test_container_arguments.cpp
+++ b/test/test_container_arguments.cpp
@@ -1,4 +1,8 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 #include <test_utility.hpp>
 
diff --git a/test/test_default_args.cpp b/test/test_default_args.cpp
index d0cdd25..61fbabc 100644
--- a/test/test_default_args.cpp
+++ b/test/test_default_args.cpp
@@ -1,7 +1,13 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
+
 #include <sstream>
 #include <streambuf>
+#include <iostream>
 
 using doctest::test_suite;
 
diff --git a/test/test_default_value.cpp b/test/test_default_value.cpp
index 15271f9..1a28168 100644
--- a/test/test_default_value.cpp
+++ b/test/test_default_value.cpp
@@ -1,4 +1,8 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 #include <string>
 
diff --git a/test/test_equals_form.cpp b/test/test_equals_form.cpp
index 81c31f8..6d95c3e 100644
--- a/test/test_equals_form.cpp
+++ b/test/test_equals_form.cpp
@@ -1,6 +1,14 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
+
 #include <iostream>
+#include <vector>
+#include <string>
+
 using doctest::test_suite;
 
 TEST_CASE("Basic --value=value" * test_suite("equals_form")) {
@@ -36,4 +44,4 @@ TEST_CASE("Basic --value=value with nargs(2)" * test_suite("equals_form")) {
   parser.parse_args({"test", "--long=value1", "value2"});
   REQUIRE((parser.get<std::vector<std::string>>("--long") ==
            std::vector<std::string>{"value1", "value2"}));
-}
\ No newline at end of file
+}
diff --git a/test/test_get.cpp b/test/test_get.cpp
index ad719b0..d2144a1 100644
--- a/test/test_get.cpp
+++ b/test/test_get.cpp
@@ -1,6 +1,12 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 
+#include <any>
+
 using doctest::test_suite;
 
 TEST_CASE("Getting a simple argument" * test_suite("ArgumentParser::get")) {
diff --git a/test/test_help.cpp b/test/test_help.cpp
index 293daef..2f29e56 100644
--- a/test/test_help.cpp
+++ b/test/test_help.cpp
@@ -1,6 +1,12 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
+
 #include <sstream>
+#include <optional>
 
 using doctest::test_suite;
 
diff --git a/test/test_invalid_arguments.cpp b/test/test_invalid_arguments.cpp
index e8db3f2..86e344c 100644
--- a/test/test_invalid_arguments.cpp
+++ b/test/test_invalid_arguments.cpp
@@ -1,4 +1,8 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 
 using doctest::test_suite;
diff --git a/test/test_is_used.cpp b/test/test_is_used.cpp
index 8d67b85..cfb6e43 100644
--- a/test/test_is_used.cpp
+++ b/test/test_is_used.cpp
@@ -1,4 +1,8 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 
 using doctest::test_suite;
diff --git a/test/test_issue_37.cpp b/test/test_issue_37.cpp
index ab9c984..7e8e2bc 100644
--- a/test/test_issue_37.cpp
+++ b/test/test_issue_37.cpp
@@ -1,4 +1,8 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 
 using doctest::test_suite;
diff --git a/test/test_negative_numbers.cpp b/test/test_negative_numbers.cpp
index fd9b1f9..f9dd463 100644
--- a/test/test_negative_numbers.cpp
+++ b/test/test_negative_numbers.cpp
@@ -1,4 +1,8 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 
 using doctest::test_suite;
diff --git a/test/test_optional_arguments.cpp b/test/test_optional_arguments.cpp
index dd9cec6..65ea25f 100644
--- a/test/test_optional_arguments.cpp
+++ b/test/test_optional_arguments.cpp
@@ -1,4 +1,8 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 
 using doctest::test_suite;
diff --git a/test/test_parent_parsers.cpp b/test/test_parent_parsers.cpp
index ffb9e00..9f9a7f8 100644
--- a/test/test_parent_parsers.cpp
+++ b/test/test_parent_parsers.cpp
@@ -1,4 +1,8 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 
 using doctest::test_suite;
diff --git a/test/test_parse_args.cpp b/test/test_parse_args.cpp
index 7a38abf..bb3af2a 100644
--- a/test/test_parse_args.cpp
+++ b/test/test_parse_args.cpp
@@ -1,6 +1,12 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 
+#include <optional>
+
 using doctest::test_suite;
 
 TEST_CASE("Missing argument" * test_suite("parse_args")) {
diff --git a/test/test_parse_known_args.cpp b/test/test_parse_known_args.cpp
index 2a9da84..d5a939c 100644
--- a/test/test_parse_known_args.cpp
+++ b/test/test_parse_known_args.cpp
@@ -1,6 +1,13 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 
+#include <vector>
+#include <string>
+
 using doctest::test_suite;
 
 TEST_CASE("Parse unknown optional and positional arguments without exceptions" *
@@ -79,4 +86,4 @@ TEST_CASE("Parse unknown optional and positional arguments in subparsers "
     REQUIRE((unknown_args == std::vector<std::string>{"--verbose", "FOO", "5",
                                                       "BAR", "-jn", "spam"}));
   }
-}
\ No newline at end of file
+}
diff --git a/test/test_positional_arguments.cpp b/test/test_positional_arguments.cpp
index cfee488..1665048 100644
--- a/test/test_positional_arguments.cpp
+++ b/test/test_positional_arguments.cpp
@@ -1,4 +1,8 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <cmath>
 #include <doctest.hpp>
 
diff --git a/test/test_prefix_chars.cpp b/test/test_prefix_chars.cpp
index e62b1d9..eb26273 100644
--- a/test/test_prefix_chars.cpp
+++ b/test/test_prefix_chars.cpp
@@ -1,4 +1,8 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <cmath>
 #include <doctest.hpp>
 
diff --git a/test/test_repr.cpp b/test/test_repr.cpp
index c09c3ac..f7330bc 100644
--- a/test/test_repr.cpp
+++ b/test/test_repr.cpp
@@ -1,6 +1,14 @@
+#ifdef WITH_MODULE
+import argparse;
+import argparse.details;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
+
 #include <set>
+#include <list>
+#include <sstream>
 
 using doctest::test_suite;
 
diff --git a/test/test_required_arguments.cpp b/test/test_required_arguments.cpp
index 299808a..7d7a077 100644
--- a/test/test_required_arguments.cpp
+++ b/test/test_required_arguments.cpp
@@ -1,4 +1,8 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 
 using doctest::test_suite;
diff --git a/test/test_scan.cpp b/test/test_scan.cpp
index 6cc53e5..4210d8f 100644
--- a/test/test_scan.cpp
+++ b/test/test_scan.cpp
@@ -1,4 +1,8 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 #include <stdint.h>
 
diff --git a/test/test_subparsers.cpp b/test/test_subparsers.cpp
index 0830ce1..9e7c29f 100644
--- a/test/test_subparsers.cpp
+++ b/test/test_subparsers.cpp
@@ -1,7 +1,14 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
-#include <cmath>
+#endif
 #include <doctest.hpp>
 
+#include <cmath>
+#include <vector>
+#include <string>
+
 using doctest::test_suite;
 
 TEST_CASE("Add subparsers" * test_suite("subparsers")) {
@@ -236,4 +243,4 @@ TEST_CASE("Check is_subcommand_used after parse" * test_suite("subparsers")) {
     REQUIRE(program.is_subcommand_used("clean") == false);
     REQUIRE(program.is_subcommand_used(command_2) == false);
   }
-}
\ No newline at end of file
+}
diff --git a/test/test_utility.hpp b/test/test_utility.hpp
index fd061de..3a596a5 100644
--- a/test/test_utility.hpp
+++ b/test/test_utility.hpp
@@ -1,6 +1,8 @@
 #ifndef ARGPARSE_TEST_UTILITY_HPP
 #define ARGPARSE_TEST_UTILITY_HPP
 
+#include <list>
+
 namespace testutility {
 // Get value at index from std::list
 template <typename T>
diff --git a/test/test_value_semantics.cpp b/test/test_value_semantics.cpp
index 2cc0f88..03e5db5 100644
--- a/test/test_value_semantics.cpp
+++ b/test/test_value_semantics.cpp
@@ -1,4 +1,8 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 
 using doctest::test_suite;
diff --git a/test/test_version.cpp b/test/test_version.cpp
index 377126e..3179f56 100644
--- a/test/test_version.cpp
+++ b/test/test_version.cpp
@@ -1,4 +1,8 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
 #include <argparse/argparse.hpp>
+#endif
 #include <doctest.hpp>
 #include <sstream>