diff --git a/cmdopt2/args.hpp b/cmdopt2/args.hpp
index 758dfe2c..b0680a24 100644
--- a/cmdopt2/args.hpp
+++ b/cmdopt2/args.hpp
@@ -22,7 +22,7 @@ namespace cruft::cmdopt2 {
     struct argument {
         std::string name;
         std::optional<std::string> description;
-        bool required = false;
+        bool required_ = false;
 
         using acceptor1_t = std::function<void(std::string_view)>;
         std::optional<acceptor1_t> acceptor1;
@@ -75,6 +75,18 @@ namespace cruft::cmdopt2 {
             res.acceptor1 = _acceptor;
             return res;
         }
+
+        bool required (void) const
+        {
+            return required_;
+        }
+
+        BaseT required (bool val) const
+        {
+            BaseT res = get ();
+            res.required_ = val;
+            return res;
+        }
     };
 
 
diff --git a/cmdopt2/parser.cpp b/cmdopt2/parser.cpp
index b2fffd2b..7de99e4f 100644
--- a/cmdopt2/parser.cpp
+++ b/cmdopt2/parser.cpp
@@ -25,7 +25,7 @@ parser::add (keyword const &arg)&
 
 ///////////////////////////////////////////////////////////////////////////////
 int
-parser::parse_named (int argc, const char *const *argv) const
+parser::parse_named (int argc, const char *const *argv, int *found) const
 {
     auto cursor = argv[0];
     if (!cursor or !*cursor)
@@ -40,9 +40,9 @@ parser::parse_named (int argc, const char *const *argv) const
         ++cursor;
         if (!*cursor)
             throw std::runtime_error ("missing long argument name");
-        return parse_long (argc, argv);
+        return parse_long (argc, argv, found);
     } else {
-        return parse_short (argc, argv);
+        return parse_short (argc, argv, found);
     }
 
     unreachable ();
@@ -51,7 +51,7 @@ parser::parse_named (int argc, const char *const *argv) const
 
 //-----------------------------------------------------------------------------
 int
-parser::parse_long (int argc, const char *const *argv) const
+parser::parse_long (int argc, const char *const *argv, int *found) const
 {
     CHECK (argc >= 1);
     CHECK (strlen (argv[0]) >= 2);
@@ -71,6 +71,8 @@ parser::parse_long (int argc, const char *const *argv) const
     if (pos == m_keyword.end ())
         throw std::runtime_error ("Unknown long argument");
 
+    found[std::distance (m_keyword.begin (), pos)] = true;
+
     if (eq) {
         (*pos->acceptor1) (eq + 1);
         return 1;
@@ -98,7 +100,7 @@ parser::parse_long (int argc, const char *const *argv) const
 
 //-----------------------------------------------------------------------------
 int
-parser::parse_short (int argc, const char *const *argv) const
+parser::parse_short (int argc, const char *const *argv, int *found) const
 {
     (void)argc;
     CHECK (argc >= 1);
@@ -123,17 +125,23 @@ parser::parse_short (int argc, const char *const *argv) const
         if (pos == m_keyword.end ())
             throw std::runtime_error ("Unknown short argument");
 
+        found[std::distance (m_keyword.begin (), pos)] = true;
+
         if (pos->acceptor0) {
             CHECK (!pos->acceptor1);
             (*pos->acceptor0) ();
             return 1;
         }
 
-        CHECK (!pos->acceptor0);
-        if (argc < 2)
-            throw std::runtime_error ("Missing short argument value");
-        (*pos->acceptor1) (argv[1]);
-        return 2;
+        if (pos->acceptor1) {
+            CHECK (!pos->acceptor0);
+            if (argc < 2)
+                throw std::runtime_error ("Missing short argument value");
+            (*pos->acceptor1) (argv[1]);
+            return 2;
+        }
+
+        return 1;
     }
 
     // Handle strings of short arguments, eg: "-vvv"
@@ -147,11 +155,13 @@ parser::parse_short (int argc, const char *const *argv) const
             });
         if (pos == m_keyword.end ())
             throw std::runtime_error ("Unknown short argument");
+        found[std::distance (m_keyword.begin (), pos)] = true;
 
         if (pos->acceptor1)
             throw std::runtime_error ("Missing short argument value");
 
-        (*pos->acceptor0) ();
+        if (pos->acceptor0)
+            (*pos->acceptor0) ();
     }
 
     return 1;
@@ -162,8 +172,8 @@ parser::parse_short (int argc, const char *const *argv) const
 int
 parser::parse (int const argc, const char *const *argv)
 {
-    if (argc <= 1)
-        return argc;
+    std::vector<int> found_positional (m_positional.size (), 0);
+    std::vector<int> found_keyword    (m_keyword.size    (), 0);
 
     using namespace std::string_view_literals;
     if (contains ("--help"sv, cruft::view (argv, argc))) {
@@ -180,13 +190,28 @@ parser::parse (int const argc, const char *const *argv)
             break;
 
         if (*arg == '-') {
-            arg_cursor += parse_named (argc - arg_cursor, argv + arg_cursor);
+            arg_cursor += parse_named (argc - arg_cursor, argv + arg_cursor, found_keyword.data ());
             continue;
         }
 
-        (*m_positional[pos_cursor].acceptor1) (argv[arg_cursor++]);
+        found_positional[pos_cursor] = true;
+        auto &pos_arg = m_positional[pos_cursor];
+        if (pos_arg.acceptor1)
+            (*pos_arg.acceptor1) (argv[arg_cursor++]);
     }
 
+    for (int i = 0, last = std::ssize (m_positional); i < last; ++i)
+        if (m_positional[i].required () and !found_positional[i])
+            throw std::runtime_error (
+                fmt::format ("Missing required position argument {}", m_positional[i].name)
+            );
+
+    for (int i = 0, last = std::ssize (m_keyword); i < last; ++i)
+        if (m_keyword[i].required () and !found_keyword[i])
+            throw std::runtime_error (
+                fmt::format ("Missing required named argument {}", m_keyword[i].name)
+            );
+
     return arg_cursor;
 }
 
@@ -209,7 +234,7 @@ usage (
     static char constexpr REQUIRED[2] { '<', '>' };
 
     for (auto const &arg: keyword) {
-        auto const &delimiters = arg.required ? REQUIRED : OPTIONAL;
+        auto const &delimiters = arg.required () ? REQUIRED : OPTIONAL;
 
         if (arg.short_) {
             fmt::print (output, FMT_STRING (" {}-{}"), delimiters[0], *arg.short_);
@@ -227,7 +252,7 @@ usage (
     }
 
     for (auto const &arg: positional) {
-        auto const &delimiters = arg.required ? REQUIRED : OPTIONAL;
+        auto const &delimiters = arg.required () ? REQUIRED : OPTIONAL;
         fmt::print (output, FMT_STRING (" {}{}{}"), delimiters[0], arg.name, delimiters[1]);
     }
 
diff --git a/cmdopt2/parser.hpp b/cmdopt2/parser.hpp
index 333b1d10..9bfbafce 100644
--- a/cmdopt2/parser.hpp
+++ b/cmdopt2/parser.hpp
@@ -17,7 +17,7 @@
 namespace cruft::cmdopt2 {
     class parser {
     public:
-        int parse (int argc, char const* const* argv);
+        int parse [[nodiscard]] (int argc, char const* const* argv);
 
         positional& add (positional const&) &;
         keyword& add (keyword const&) &;
@@ -26,9 +26,9 @@ namespace cruft::cmdopt2 {
         void usage (int argc, char const * const* argv, std::ostream&) const;
 
     private:
-        int parse_named (int argc, char const* const* argv) const;
-        int parse_short (int argc, char const* const* argv) const;
-        int parse_long  (int argc, char const* const* argv) const;
+        int parse_named (int argc, char const* const* argv, int*) const;
+        int parse_short (int argc, char const* const* argv, int*) const;
+        int parse_long  (int argc, char const* const* argv, int*) const;
 
         std::vector<positional> m_positional;
         std::vector<keyword> m_keyword;
diff --git a/test/cmdopt2.cpp b/test/cmdopt2.cpp
index 87d3ca1f..d8df85dd 100644
--- a/test/cmdopt2.cpp
+++ b/test/cmdopt2.cpp
@@ -93,10 +93,13 @@ test_combinations (cruft::TAP::logger &tap)
         qux = decltype(qux) {};
         verbose = false;
 
-        p.parse (int (t.args.size ()), t.args.data ());
+        auto const consumed = p.parse (int (t.args.size ()), t.args.data ());
 
         tap.expect (
-            foo == t.foo and bar == t.bar and qux == t.qux,
+            consumed == int (t.args.size ())
+                and foo == t.foo
+                and bar == t.bar
+                and qux == t.qux,
             "{}", fmt::join (t.args.begin (), t.args.end (), " ")
         );
     }
@@ -171,21 +174,61 @@ static void test_presence (cruft::TAP::logger &tap)
         count   = 0;
         present = false;
 
-        p.parse (int (t.args.size ()), t.args.data ());
+        auto const consumed = p.parse (int (t.args.size ()), t.args.data ());
 
         tap.expect (
-            count == t.count and present == t.present,
+            consumed == int (t.args.size ())
+                and count == t.count
+                and present == t.present,
             "{}", fmt::join (t.args.begin (), t.args.end (), " ")
         );
     }
 }
 
 
+///////////////////////////////////////////////////////////////////////////////
+static void
+test_required (cruft::TAP::logger &tap)
+{
+    static const struct {
+        std::vector<char const*> args;
+        bool success;
+    } TESTS[] = {
+        { .args = { "cmd",      }, .success = false },
+        { .args = { "cmd", "-y" }, .success = true  },
+        { .args = { "cmd", "-n" }, .success = false },
+    };
+
+    using namespace cruft::cmdopt2;
+
+    parser p;
+    p.add (keyword::create ("y").flag ('y').required (true ).ignore ());
+    p.add (keyword::create ("n").flag ('n').required (false).ignore ());
+
+    for (auto const &t: TESTS) {
+        bool success;
+        try {
+            auto const consumed  = p.parse (int (t.args.size ()), t.args.data ());
+            bool const completed = consumed == int (t.args.size ());
+            success = completed == t.success;
+        } catch (...) {
+            success = not t.success;
+        }
+        tap.expect (
+            success,
+            "{}",
+            fmt::join (t.args.begin (), t.args.end (), " ")
+        );
+    }
+}
+
+
 ///////////////////////////////////////////////////////////////////////////////
 int main ()
 {
     cruft::TAP::logger tap;
     test_combinations (tap);
     test_presence (tap);
+    test_required (tap);
     return tap.status ();
 }
\ No newline at end of file