diff --git a/src/testdir/test_vim9_class.vim b/src/testdir/test_vim9_class.vim
index cd67b54..684bf6d 100644
--- a/src/testdir/test_vim9_class.vim
+++ b/src/testdir/test_vim9_class.vim
@@ -135,6 +135,16 @@
   END
   v9.CheckScriptFailure(lines, 'E1069:')
 
+  # Test for unsupported comment specifier
+  lines =<< trim END
+    vim9script
+    class Something
+      # comment
+      #{
+    endclass
+  END
+  v9.CheckScriptFailure(lines, 'E1170:')
+
   lines =<< trim END
       vim9script
 
@@ -162,6 +172,44 @@
       assert_equal('object<TextPosition>', typename(pos))
   END
   v9.CheckScriptSuccess(lines)
+
+  # When referencing object methods, space cannot be used after a "."
+  lines =<< trim END
+    vim9script
+    class A
+      def Foo(): number
+        return 10
+      enddef
+    endclass
+    var a = A.new()
+    var v = a. Foo()
+  END
+  v9.CheckScriptFailure(lines, 'E1202:')
+
+  # Using an object without specifying a method or a member variable
+  lines =<< trim END
+    vim9script
+    class A
+      def Foo(): number
+        return 10
+      enddef
+    endclass
+    var a = A.new()
+    var v = a.
+  END
+  v9.CheckScriptFailure(lines, 'E15:')
+
+  # Error when parsing the arguments of an object method.
+  lines =<< trim END
+    vim9script
+    class A
+      def Foo()
+      enddef
+    endclass
+    var a = A.new()
+    var v = a.Foo(,)
+  END
+  v9.CheckScriptFailure(lines, 'E15:')
 enddef
 
 def Test_class_defined_twice()
@@ -628,6 +676,15 @@
       endclass
   END
   v9.CheckScriptFailure(lines, 'E1330:')
+
+  # Test for initializing an object member with an unknown variable/type
+  lines =<< trim END
+    vim9script
+    class A
+       this.value = init_val
+    endclass
+  END
+  v9.CheckScriptFailureList(lines, ['E121:', 'E1329:'])
 enddef
 
 def Test_class_object_member_access()
@@ -658,6 +715,15 @@
   END
   v9.CheckScriptSuccess(lines)
 
+  # Test for a public member variable name beginning with an underscore
+  lines =<< trim END
+    vim9script
+    class A
+      public this._val = 10
+    endclass
+  END
+  v9.CheckScriptFailure(lines, 'E1332:')
+
   lines =<< trim END
       vim9script
 
@@ -735,6 +801,33 @@
             .x
   END
   v9.CheckScriptSuccess(lines)
+
+  # Test for "public" cannot be abbreviated
+  lines =<< trim END
+    vim9script
+    class Something
+      pub this.val = 1
+    endclass
+  END
+  v9.CheckScriptFailure(lines, 'E1065:')
+
+  # Test for "public" keyword must be followed by "this" or "static".
+  lines =<< trim END
+    vim9script
+    class Something
+      public val = 1
+    endclass
+  END
+  v9.CheckScriptFailure(lines, 'E1331:')
+
+  # Test for "static" cannot be abbreviated
+  lines =<< trim END
+    vim9script
+    class Something
+      stat this.val = 1
+    endclass
+  END
+  v9.CheckScriptFailure(lines, 'E1065:')
 enddef
 
 def Test_class_object_compare()
@@ -1002,6 +1095,42 @@
       s.Method(7)
   END
   v9.CheckScriptFailure(lines, 'E1341: Variable already declared in the class: count')
+
+  # Test for using an invalid type for a member variable
+  lines =<< trim END
+    vim9script
+    class A
+      this.val: xxx
+    endclass
+  END
+  v9.CheckScriptFailure(lines, 'E1010:')
+
+  # Test for no space before or after the '=' when initializing a member
+  # variable
+  lines =<< trim END
+    vim9script
+    class A
+      this.val: number= 10
+    endclass
+  END
+  v9.CheckScriptFailure(lines, 'E1004:')
+  lines =<< trim END
+    vim9script
+    class A
+      this.val: number =10
+    endclass
+  END
+  v9.CheckScriptFailure(lines, 'E1004:')
+
+  # Access a non-existing member
+  lines =<< trim END
+    vim9script
+    class A
+    endclass
+    var a = A.new()
+    var v = a.bar
+  END
+  v9.CheckScriptFailure(lines, 'E1326:')
 enddef
 
 func Test_class_garbagecollect()
@@ -1072,6 +1201,18 @@
       assert_equal(2, Value.GetCount())
   END
   v9.CheckScriptSuccess(lines)
+
+  # Test for cleaning up after a class definition failure when using class
+  # functions.
+  lines =<< trim END
+    vim9script
+    class A
+      static def Foo()
+      enddef
+      aaa
+    endclass
+  END
+  v9.CheckScriptFailure(lines, 'E1318:')
 enddef
 
 def Test_class_defcompile()
@@ -1100,6 +1241,40 @@
       defcompile C.Fc
   END
   v9.CheckScriptFailure(lines, 'E1012: Type mismatch; expected number but got string')
+
+  # Trying to compile a function using a non-existing class variable
+  lines =<< trim END
+    vim9script
+    defcompile x.Foo()
+  END
+  v9.CheckScriptFailure(lines, 'E475:')
+
+  # Trying to compile a function using a variable which is not a class
+  lines =<< trim END
+    vim9script
+    var x: number
+    defcompile x.Foo()
+  END
+  v9.CheckScriptFailure(lines, 'E475:')
+
+  # Trying to compile a function without specifying the name
+  lines =<< trim END
+    vim9script
+    class A
+    endclass
+    defcompile A.
+  END
+  v9.CheckScriptFailure(lines, 'E475:')
+
+  # Trying to compile a non-existing class object member function
+  lines =<< trim END
+    vim9script
+    class A
+    endclass
+    var a = A.new()
+    defcompile a.Foo()
+  END
+  v9.CheckScriptFailureList(lines, ['E1334:', 'E475:'])
 enddef
 
 def Test_class_object_to_string()
@@ -1345,6 +1520,62 @@
       Test()
   END
   v9.CheckScriptSuccess(lines)
+
+  # Interface name after "extends" doesn't end in a space or NUL character
+  lines =<< trim END
+    vim9script
+    interface A
+    endinterface
+    class B extends A"
+    endclass
+  END
+  v9.CheckScriptFailure(lines, 'E1315:')
+
+  # Trailing characters after a class name
+  lines =<< trim END
+    vim9script
+    class A bbb
+    endclass
+  END
+  v9.CheckScriptFailure(lines, 'E488:')
+
+  # using "implements" with a non-existing class
+  lines =<< trim END
+    vim9script
+    class A implements B
+    endclass
+  END
+  v9.CheckScriptFailure(lines, 'E1346:')
+
+  # using "implements" with a regular class
+  lines =<< trim END
+    vim9script
+    class A
+    endclass
+    class B implements A
+    endclass
+  END
+  v9.CheckScriptFailure(lines, 'E1347:')
+
+  # using "implements" with a variable
+  lines =<< trim END
+    vim9script
+    var T: number = 10
+    class A implements T
+    endclass
+  END
+  v9.CheckScriptFailure(lines, 'E1347:')
+
+  # all the class methods in an "interface" should be implemented
+  lines =<< trim END
+    vim9script
+    interface A
+      static def Foo()
+    endinterface
+    class B implements A
+    endclass
+  END
+  v9.CheckScriptFailure(lines, 'E1349:')
 enddef
 
 def Test_call_interface_method()
@@ -1717,6 +1948,16 @@
       assert_equal("object of Success {success: true, value: 'asdf'}", string(v))
   END
   v9.CheckScriptSuccess(lines)
+
+  # class name after "extends" doesn't end in a space or NUL character
+  lines =<< trim END
+    vim9script
+    class A
+    endclass
+    class B extends A"
+    endclass
+  END
+  v9.CheckScriptFailure(lines, 'E1315:')
 enddef
 
 def Test_using_base_class()
@@ -1841,6 +2082,16 @@
       endclass
   END
   v9.CheckScriptFailure(lines, 'E1316:')
+
+  # Abstract class cannot have a "new" function
+  lines =<< trim END
+    vim9script
+    abstract class Base
+      def new()
+      enddef
+    endclass
+  END
+  v9.CheckScriptFailure(lines, 'E1359:')
 enddef
 
 def Test_closure_in_class()
@@ -2063,4 +2314,127 @@
   v9.CheckScriptSuccess(lines)
 enddef
 
+" Test for calling methods from three levels of classes
+def Test_multi_level_method_call()
+  var lines =<< trim END
+    vim9script
+
+    var A_func1: number = 0
+    var A_func2: number = 0
+    var A_func3: number = 0
+    var B_func2: number = 0
+    var B_func3: number = 0
+    var C_func3: number = 0
+
+    class A
+      def Func1()
+        A_func1 += 1
+      enddef
+
+      def Func2()
+        A_func2 += 1
+      enddef
+
+      def Func3()
+        A_func3 += 1
+      enddef
+    endclass
+
+    class B extends A
+      def Func2()
+        B_func2 += 1
+      enddef
+
+      def Func3()
+        B_func3 += 1
+      enddef
+    endclass
+
+    class C extends B
+      def Func3()
+        C_func3 += 1
+      enddef
+    endclass
+
+    def A_CallFuncs(a: A)
+      a.Func1()
+      a.Func2()
+      a.Func3()
+    enddef
+
+    def B_CallFuncs(b: B)
+      b.Func1()
+      b.Func2()
+      b.Func3()
+    enddef
+
+    def C_CallFuncs(c: C)
+      c.Func1()
+      c.Func2()
+      c.Func3()
+    enddef
+
+    var cobj = C.new()
+    A_CallFuncs(cobj)
+    B_CallFuncs(cobj)
+    C_CallFuncs(cobj)
+    assert_equal(3, A_func1)
+    assert_equal(0, A_func2)
+    assert_equal(0, A_func3)
+    assert_equal(3, B_func2)
+    assert_equal(0, B_func3)
+    assert_equal(3, C_func3)
+  END
+  v9.CheckScriptSuccess(lines)
+enddef
+
+" Test for using members from three levels of classes
+def Test_multi_level_member_access()
+  var lines =<< trim END
+    vim9script
+
+    class A
+      this.val1: number = 0
+      this.val2: number = 0
+      this.val3: number = 0
+    endclass
+
+    class B extends A
+      this.val2: number = 0
+      this.val3: number = 0
+    endclass
+
+    class C extends B
+      this.val3: number = 0
+    endclass
+
+    def A_members(a: A)
+      a.val1 += 1
+      a.val2 += 1
+      a.val3 += 1
+    enddef
+
+    def B_members(b: B)
+      b.val1 += 1
+      b.val2 += 1
+      b.val3 += 1
+    enddef
+
+    def C_members(c: C)
+      c.val1 += 1
+      c.val2 += 1
+      c.val3 += 1
+    enddef
+
+    var cobj = C.new()
+    A_members(cobj)
+    B_members(cobj)
+    C_members(cobj)
+    assert_equal(3, cobj.val1)
+    assert_equal(3, cobj.val2)
+    assert_equal(3, cobj.val3)
+  END
+  v9.CheckScriptSuccess(lines)
+enddef
+
 " vim: ts=8 sw=2 sts=2 expandtab tw=80 fdm=marker
diff --git a/src/version.c b/src/version.c
index f120730..325a46e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1737,
+/**/
     1736,
 /**/
     1735,
diff --git a/src/vim9class.c b/src/vim9class.c
index b04fb0f..e310dec 100644
--- a/src/vim9class.c
+++ b/src/vim9class.c
@@ -231,6 +231,117 @@
 }
 
 /*
+ * Update the interface class lookup table for the member index on the
+ * interface to the member index in the class implementing the interface.
+ * And a lookup table for the object method index on the interface
+ * to the object method index in the class implementing the interface.
+ * This is also used for updating the lookup table for the extended class
+ * hierarchy.
+ */
+    static int
+update_member_method_lookup_table(
+	class_T		*ifcl,
+	class_T		*cl,
+	garray_T	*objmethods,
+	int		pobj_method_offset,
+	int		is_interface)
+{
+    if (ifcl == NULL)
+	return OK;
+
+    // Table for members.
+    itf2class_T *if2cl = alloc_clear(sizeof(itf2class_T)
+	    + ifcl->class_obj_member_count * sizeof(int));
+    if (if2cl == NULL)
+	return FAIL;
+    if2cl->i2c_next = ifcl->class_itf2class;
+    ifcl->class_itf2class = if2cl;
+    if2cl->i2c_class = cl;
+    if2cl->i2c_is_method = FALSE;
+
+    for (int if_i = 0; if_i < ifcl->class_obj_member_count; ++if_i)
+	for (int cl_i = 0; cl_i < cl->class_obj_member_count; ++cl_i)
+	{
+	    if (STRCMP(ifcl->class_obj_members[if_i].ocm_name,
+			cl->class_obj_members[cl_i].ocm_name) == 0)
+	    {
+		int *table = (int *)(if2cl + 1);
+		table[if_i] = cl_i;
+		break;
+	    }
+	}
+
+    // Table for methods.
+    if2cl = alloc_clear(sizeof(itf2class_T)
+	    + ifcl->class_obj_method_count * sizeof(int));
+    if (if2cl == NULL)
+	return FAIL;
+    if2cl->i2c_next = ifcl->class_itf2class;
+    ifcl->class_itf2class = if2cl;
+    if2cl->i2c_class = cl;
+    if2cl->i2c_is_method = TRUE;
+
+    for (int if_i = 0; if_i < ifcl->class_obj_method_count; ++if_i)
+    {
+	int done = FALSE;
+	for (int cl_i = 0; cl_i < objmethods->ga_len; ++cl_i)
+	{
+	    if (STRCMP(ifcl->class_obj_methods[if_i]->uf_name,
+			((ufunc_T **)objmethods->ga_data)[cl_i]->uf_name)
+		    == 0)
+	    {
+		int *table = (int *)(if2cl + 1);
+		table[if_i] = cl_i;
+		done = TRUE;
+		break;
+	    }
+	}
+
+	// extended class object method is not overridden by the child class.
+	// Keep the method declared in one of the parent classes in the
+	// lineage.
+	if (!done && !is_interface)
+	{
+	    // If "ifcl" is not the immediate parent of "cl", then search in
+	    // the intermediate parent classes.
+	    if (cl->class_extends != ifcl)
+	    {
+		class_T	    *parent = cl->class_extends;
+		int	    method_offset = objmethods->ga_len;
+
+		while (!done && parent != NULL && parent != ifcl)
+		{
+
+		    for (int cl_i = 0;
+			    cl_i < parent->class_obj_method_count_child; ++cl_i)
+		    {
+			if (STRCMP(ifcl->class_obj_methods[if_i]->uf_name,
+				    parent->class_obj_methods[cl_i]->uf_name)
+				== 0)
+			{
+			    int *table = (int *)(if2cl + 1);
+			    table[if_i] = method_offset + cl_i;
+			    done = TRUE;
+			    break;
+			}
+		    }
+		    method_offset += parent->class_obj_method_count_child;
+		    parent = parent->class_extends;
+		}
+	    }
+
+	    if (!done)
+	    {
+		int *table = (int *)(if2cl + 1);
+		table[if_i] = pobj_method_offset + if_i;
+	    }
+	}
+    }
+
+    return OK;
+}
+
+/*
  * Handle ":class" and ":abstract class" up to ":endclass".
  * Handle ":interface" up to ":endinterface".
  */
@@ -534,6 +645,7 @@
 		{
 		    emsg(_(e_cannot_define_new_function_in_abstract_class));
 		    success = FALSE;
+		    func_clear_free(uf, FALSE);
 		    break;
 		}
 		garray_T *fgap = has_static || is_new
@@ -654,6 +766,8 @@
 	    {
 		semsg(_(e_not_valid_interface_str), impl);
 		success = FALSE;
+		clear_tv(&tv);
+		break;
 	    }
 
 	    class_T *ifcl = tv.vval.v_class;
@@ -839,83 +953,35 @@
 
 	if (cl->class_interface_count > 0 || extends_cl != NULL)
 	{
-	    // For each interface add a lookuptable for the member index on the
-	    // interface to the member index in this class.
-	    // And a lookuptable for the object method index on the interface
+	    // For each interface add a lookup table for the member index on
+	    // the interface to the member index in this class.
+	    // And a lookup table for the object method index on the interface
 	    // to the object method index in this class.
-	    // Also do this for the extended class, if any.
-	    for (int i = 0; i <= cl->class_interface_count; ++i)
+	    for (int i = 0; i < cl->class_interface_count; ++i)
 	    {
-		class_T *ifcl = i < cl->class_interface_count
-					    ? cl->class_interfaces_cl[i]
-					    : extends_cl;
-		if (ifcl == NULL)
-		    continue;
+		class_T *ifcl = cl->class_interfaces_cl[i];
 
-		// Table for members.
-		itf2class_T *if2cl = alloc_clear(sizeof(itf2class_T)
-				 + ifcl->class_obj_member_count * sizeof(int));
-		if (if2cl == NULL)
+		if (update_member_method_lookup_table(ifcl, cl, &objmethods,
+			    0, TRUE) == FAIL)
 		    goto cleanup;
-		if2cl->i2c_next = ifcl->class_itf2class;
-		ifcl->class_itf2class = if2cl;
-		if2cl->i2c_class = cl;
-		if2cl->i2c_is_method = FALSE;
+	    }
 
-		for (int if_i = 0; if_i < ifcl->class_obj_member_count; ++if_i)
-		    for (int cl_i = 0; cl_i < cl->class_obj_member_count;
-									++cl_i)
-		    {
-			if (STRCMP(ifcl->class_obj_members[if_i].ocm_name,
-				    cl->class_obj_members[cl_i].ocm_name) == 0)
-			{
-			    int *table = (int *)(if2cl + 1);
-			    table[if_i] = cl_i;
-			    break;
-			}
-		    }
+	    // Update the lookup table for the extended class, if nay
+	    if (extends_cl != NULL)
+	    {
+		class_T		*pclass = extends_cl;
+		int		pobj_method_offset = objmethods.ga_len;
 
-		// Table for methods.
-		if2cl = alloc_clear(sizeof(itf2class_T)
-				 + ifcl->class_obj_method_count * sizeof(int));
-		if (if2cl == NULL)
-		    goto cleanup;
-		if2cl->i2c_next = ifcl->class_itf2class;
-		ifcl->class_itf2class = if2cl;
-		if2cl->i2c_class = cl;
-		if2cl->i2c_is_method = TRUE;
-
-		for (int if_i = 0; if_i < ifcl->class_obj_method_count; ++if_i)
+		// Update the entire lineage of extended classes.
+		while (pclass != NULL)
 		{
-		    int done = FALSE;
-		    for (int cl_i = 0; cl_i < objmethods.ga_len; ++cl_i)
-		    {
-			if (STRCMP(ifcl->class_obj_methods[if_i]->uf_name,
-			       ((ufunc_T **)objmethods.ga_data)[cl_i]->uf_name)
-									  == 0)
-			{
-			    int *table = (int *)(if2cl + 1);
-			    table[if_i] = cl_i;
-			    done = TRUE;
-			    break;
-			}
-		    }
+		    if (update_member_method_lookup_table(pclass, cl,
+				&objmethods, pobj_method_offset, FALSE) ==
+			    FAIL)
+			goto cleanup;
 
-		    if (!done && extends_cl != NULL)
-		    {
-			for (int cl_i = 0;
-			     cl_i < extends_cl->class_obj_method_count; ++cl_i)
-			{
-			    if (STRCMP(ifcl->class_obj_methods[if_i]->uf_name,
-				   extends_cl->class_obj_methods[cl_i]->uf_name)
-									  == 0)
-			    {
-				int *table = (int *)(if2cl + 1);
-				table[if_i] = objmethods.ga_len + cl_i;
-				break;
-			    }
-			}
-		    }
+		    pobj_method_offset += pclass->class_obj_method_count_child;
+		    pclass = pclass->class_extends;
 		}
 	    }
 	}