diff --git a/src/gsi/gsi/gsiMethods.cc b/src/gsi/gsi/gsiMethods.cc
index 717ce0389..95a02b5ca 100644
--- a/src/gsi/gsi/gsiMethods.cc
+++ b/src/gsi/gsi/gsiMethods.cc
@@ -195,7 +195,7 @@ type_to_s (const gsi::ArgType &a, bool for_return)
     s += "[]";
     break;
   case gsi::T_map:
-    s += "map<";
+    s += "map<";
     if (a.inner_k ()) {
       s += type_to_s (*a.inner_k (), false);
     }
@@ -203,7 +203,7 @@ type_to_s (const gsi::ArgType &a, bool for_return)
     if (a.inner ()) {
       s += type_to_s (*a.inner (), false);
     }
-    s += "&gt;";
+    s += ">";
     break;
   }
   if (a.is_cptr () || a.is_ptr ()) {
diff --git a/src/pya/pya/pyaCallables.cc b/src/pya/pya/pyaCallables.cc
index d35f8bff9..3ab826f9c 100644
--- a/src/pya/pya/pyaCallables.cc
+++ b/src/pya/pya/pyaCallables.cc
@@ -708,7 +708,7 @@ push_args (gsi::SerialArgs &arglist, const gsi::MethodBase *meth, PyObject *args
           tl::Variant def_value = a->spec ()->default_value ();
           gsi::push_arg (arglist, *a, def_value, &heap);
         } else {
-          throw tl::Exception (tl::to_string ("No argument provided (positional or keyword) and no default value available"));
+          throw tl::Exception (tl::to_string (tr ("No argument provided (positional or keyword) and no default value available")));
         }
       } else {
         if (iarg >= argc) {
@@ -809,6 +809,10 @@ method_adaptor (int mid, PyObject *self, PyObject *args, PyObject *kwargs)
     //  handle special methods
     if (meth->smt () != gsi::MethodBase::None) {
 
+      if (kwargs != NULL && PyDict_Size (kwargs) > 0) {
+        throw tl::Exception (tl::to_string (tr ("Keyword arguments not permitted")));
+      }
+
       ret = special_method_impl (meth->smt (), self, args);
 
     } else {
@@ -936,6 +940,10 @@ method_init_adaptor (int mid, PyObject *self, PyObject *args, PyObject *kwargs)
 
     } else {
 
+      if (kwargs != NULL && PyDict_Size (kwargs) > 0) {
+        throw tl::Exception (tl::to_string (tr ("Keyword arguments not permitted")));
+      }
+
       //  No action required - the object is default-created later once it is really required.
       if (! PyArg_ParseTuple (args, "")) {
         return NULL;
diff --git a/src/rba/rba/rba.cc b/src/rba/rba/rba.cc
index bc40e237c..04e0f37f2 100644
--- a/src/rba/rba/rba.cc
+++ b/src/rba/rba/rba.cc
@@ -176,9 +176,9 @@ static VALUE
 get_kwarg (const gsi::ArgType &atype, VALUE kwargs)
 {
   if (kwargs != Qnil) {
-    return rb_hash_lookup2 (kwargs, rb_id2sym (rb_intern (atype.spec ()->name ().c_str ())), Qnil);
+    return rb_hash_lookup2 (kwargs, rb_id2sym (rb_intern (atype.spec ()->name ().c_str ())), Qundef);
   } else {
-    return Qnil;
+    return Qundef;
   }
 }
 
@@ -477,7 +477,7 @@ private:
           int i = 0;
           for (gsi::MethodBase::argument_iterator a = (*m)->begin_arguments (); is_valid && a != (*m)->end_arguments (); ++a, ++i) {
             VALUE arg = i >= argc ? get_kwarg (*a, kwargs) : argv[i];
-            if (arg == Qnil) {
+            if (arg == Qundef) {
               is_valid = a->spec ()->has_default ();
             } else if (test_arg (*a, arg, false /*strict*/)) {
               ++sc;
@@ -1060,7 +1060,7 @@ push_args (gsi::SerialArgs &arglist, const gsi::MethodBase *meth, VALUE *argv, i
     for (gsi::MethodBase::argument_iterator a = meth->begin_arguments (); a != meth->end_arguments (); ++a, ++iarg) {
 
       VALUE arg = iarg >= argc ? get_kwarg (*a, kwargs) : argv[iarg];
-      if (arg == Qnil) {
+      if (arg == Qundef) {
         if (a->spec ()->has_default ()) {
           if (kwargs_taken == nkwargs) {
             //  leave it to the consumer to establish the default values (that is faster)
@@ -1069,7 +1069,7 @@ push_args (gsi::SerialArgs &arglist, const gsi::MethodBase *meth, VALUE *argv, i
           tl::Variant def_value = a->spec ()->default_value ();
           gsi::push_arg (arglist, *a, def_value, &heap);
         } else {
-          throw tl::Exception (tl::to_string ("No argument provided (positional or keyword) and no default value available"));
+          throw tl::Exception (tl::to_string (tr ("No argument provided (positional or keyword) and no default value available")));
         }
       } else {
         if (iarg >= argc) {
@@ -1195,10 +1195,18 @@ method_adaptor (int mid, int argc, VALUE *argv, VALUE self, bool ctor)
 
     } else if (meth->smt () != gsi::MethodBase::None) {
 
+      if (kwargs != Qnil && rb_hash_size_num (kwargs) > 0) {
+        throw tl::Exception (tl::to_string (tr ("Keyword arguments not permitted")));
+      }
+
       ret = special_method_impl (meth, argc, argv, self, ctor);
 
     } else if (meth->is_signal ()) {
 
+      if (kwargs != Qnil && rb_hash_size_num (kwargs) > 0) {
+        throw tl::Exception (tl::to_string (tr ("Keyword arguments not permitted on events")));
+      }
+
       if (p) {
 
         static ID id_set = rb_intern ("set");
@@ -1245,6 +1253,10 @@ method_adaptor (int mid, int argc, VALUE *argv, VALUE self, bool ctor)
 
       //  calling an iterator method without block -> deliver an enumerator using "to_enum"
 
+      if (kwargs != Qnil && rb_hash_size_num (kwargs) > 0) {
+        throw tl::Exception (tl::to_string (tr ("Keyword arguments not permitted on enumerators")));
+      }
+
       static ID id_to_enum = rb_intern ("to_enum");
 
       VALUE method_sym = ID2SYM (rb_intern (meth->primary_name ().c_str ()));
diff --git a/testdata/python/kwargs.py b/testdata/python/kwargs.py
index 8f30b95d9..23bd87800 100644
--- a/testdata/python/kwargs.py
+++ b/testdata/python/kwargs.py
@@ -172,6 +172,14 @@ class KWArgsTest(unittest.TestCase):
     except Exception as ex:
       self.assertEqual(str(ex), "Value cannot be converted to a floating-point value for argument #2 ('dbu') in CplxTrans.to_s")
 
+    try:
+      t = pya.CplxTrans(1.5, 2.5)
+      tt = pya.CplxTrans()
+      tt.assign(other = t)
+      self.assertEqual(True, False)
+    except Exception as ex:
+      self.assertEqual(str(ex), "Keyword arguments not permitted in CplxTrans.assign")
+
     try:
       t = pya.CplxTrans("17")
       self.assertEqual(True, False)
diff --git a/testdata/ruby/kwargs.rb b/testdata/ruby/kwargs.rb
index 9a52cfc06..4299aab9c 100644
--- a/testdata/ruby/kwargs.rb
+++ b/testdata/ruby/kwargs.rb
@@ -180,6 +180,15 @@ class KWArgs_TestClass < TestBase
       assert_equal(ex.to_s, "TypeError: no implicit conversion to float from string for argument #2 ('dbu') in CplxTrans::to_s")
     end
 
+    begin
+      t = RBA::CplxTrans::new(1.5, 2.5)
+      tt = RBA::CplxTrans::new
+      tt.assign(other: t)
+      assert_equal(true, false)
+    rescue => ex
+      assert_equal(ex.to_s, "Keyword arguments not permitted in CplxTrans::assign")
+    end
+
     begin
       t = RBA::CplxTrans::new("17")
       assert_equal(true, false)
diff --git a/testdata/ruby/tlTest.rb b/testdata/ruby/tlTest.rb
index 8980b2ec5..6a6f996d6 100644
--- a/testdata/ruby/tlTest.rb
+++ b/testdata/ruby/tlTest.rb
@@ -301,10 +301,10 @@ class Tl_TestClass < TestBase
     assert_equal(my_recipe.name, "rba_test_recipe")
     assert_equal(my_recipe.description, "description")
 
-    g = my_recipe.generator("A" => 6, "B" => 7.0)
+    g = my_recipe.generator({ "A" => 6, "B" => 7.0 })
     assert_equal(g, "rba_test_recipe: A=#6,B=##7")
     assert_equal("%g" % RBA::Recipe::make(g), "42")
-    assert_equal("%g" % RBA::Recipe::make(g, "C" => 1.5).to_s, "63")
+    assert_equal("%g" % RBA::Recipe::make(g, { "C" => 1.5 }).to_s, "63")
 
     my_recipe._destroy
     my_recipe = nil