diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 300bf2b95c..e7e5296233 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -35,6 +35,8 @@ mut:
 	// checked_ident  string // to avoid infinit checker loops
 	var_decl_name  string
 	returns        bool
+	mod string  // current module name
+	is_builtin_mod bool // are we in `builtin`?
 }
 
 pub fn new_checker(table &table.Table, pref &pref.Preferences) Checker {
@@ -150,7 +152,7 @@ pub fn (c mut Checker) struct_init(struct_init mut ast.StructInit) table.Type {
 						}
 					}
 					if !exists {
-						c.error('struct init: no such field `$field.name` for struct `$type_sym.name`', field.pos)
+						c.error('unknown field `$field.name` in struct literal of type `$type_sym.name`', field.pos)
 						continue
 					}
 					if field_name in inited_fields {
@@ -320,6 +322,12 @@ pub fn (c mut Checker) call_method(call_expr mut ast.CallExpr) table.Type {
 		return info.elem_type
 	}
 	if method := c.table.type_find_method(left_type_sym, method_name) {
+		if !method.is_pub && !c.is_builtin_mod && left_type_sym.mod != c.mod && left_type_sym.mod != '' { // method.mod != c.mod {
+			// If a private method is called outside of the module
+			// its receiver type is defined in, show an error.
+			//println('warn $method_name lef.mod=$left_type_sym.mod c.mod=$c.mod')
+			c.error('method `${left_type_sym.name}.$method_name` is private', call_expr.pos)
+		}
 		no_args := method.args.len - 1
 		min_required_args := method.args.len - if method.is_variadic && method.args.len > 1 { 2 } else { 1 }
 		if call_expr.args.len < min_required_args {
@@ -1012,6 +1020,11 @@ fn (c mut Checker) stmt(node ast.Stmt) {
 		}
 		// ast.HashStmt {}
 		ast.Import {}
+		ast.Module {
+			c.mod = it.name
+			c.is_builtin_mod = it.name == 'builtin'
+		}
+
 		// ast.GlobalDecl {}
 		ast.Return {
 			c.returns = true
@@ -1635,7 +1648,14 @@ fn (c mut Checker) warn_or_error(message string, pos token.Position, warn bool)
 	// if c.pref.is_verbose {
 	// print_backtrace()
 	// }
-	if !warn {
+	if warn {
+		c.warnings << scanner.Warning{
+			reporter: scanner.Reporter.checker
+			pos: pos
+			file_path: c.file.path
+			message: message
+		}
+	} else {
 		c.nr_errors++
 		if !(pos.line_nr in c.error_lines) {
 			c.errors << scanner.Error{
@@ -1646,16 +1666,10 @@ fn (c mut Checker) warn_or_error(message string, pos token.Position, warn bool)
 			}
 			c.error_lines << pos.line_nr
 		}
-	} else {
-		c.warnings << scanner.Warning{
-			reporter: scanner.Reporter.checker
-			pos: pos
-			file_path: c.file.path
-			message: message
-		}
 	}
 }
 
+// for debugging only
 fn (p Checker) fileis(s string) bool {
 	return p.file.path.contains(s)
 }
diff --git a/vlib/v/checker/tests/inout/struct_unknown_field.out b/vlib/v/checker/tests/inout/struct_unknown_field.out
index 9f6f87ab24..68365cdccb 100644
--- a/vlib/v/checker/tests/inout/struct_unknown_field.out
+++ b/vlib/v/checker/tests/inout/struct_unknown_field.out
@@ -1,7 +1,7 @@
-vlib/v/checker/tests/inout/struct_unknown_field.v:8:9: error: struct init: no such field `bar` for struct `Test`
+vlib/v/checker/tests/inout/struct_unknown_field.v:8:9: error: unknown field `bar` in struct literal `Test`
     6|     t := Test{
     7|         foo: true
     8|         bar: false
                ^
     9|     }
-   10| }
\ No newline at end of file
+   10| }
diff --git a/vlib/v/parser/fn.v b/vlib/v/parser/fn.v
index f1ff03f5de..90e3a1d82d 100644
--- a/vlib/v/parser/fn.v
+++ b/vlib/v/parser/fn.v
@@ -180,6 +180,7 @@ fn (var p Parser) fn_decl() ast.FnDecl {
 			return_type: return_type
 			is_variadic: is_variadic
 			is_generic: is_generic
+			is_pub: is_pub
 		})
 	} else {
 		if is_c {
@@ -200,6 +201,7 @@ fn (var p Parser) fn_decl() ast.FnDecl {
 			is_c: is_c
 			is_js: is_js
 			is_generic: is_generic
+			is_pub: is_pub
 		})
 	}
 	// Body
diff --git a/vlib/v/parser/parser.v b/vlib/v/parser/parser.v
index b22a240fe9..271f039b63 100644
--- a/vlib/v/parser/parser.v
+++ b/vlib/v/parser/parser.v
@@ -26,8 +26,8 @@ mut:
 	inside_for        bool
 	inside_fn         bool
 	pref              &pref.Preferences
-	builtin_mod       bool
-	mod               string
+	builtin_mod       bool // are we in the `builtin` module?
+	mod               string // current module name
 	attr              string
 	expr_mod          string
 	scope             &ast.Scope
@@ -1690,6 +1690,7 @@ fn (var p Parser) struct_decl() ast.StructDecl {
 			is_typedef: is_typedef
 			is_union: is_union
 		}
+		mod: p.mod
 	}
 	var ret := 0
 	if p.builtin_mod && t.name in table.builtin_type_names {
diff --git a/vlib/v/table/atypes.v b/vlib/v/table/atypes.v
index b52feff73a..6809b90c15 100644
--- a/vlib/v/table/atypes.v
+++ b/vlib/v/table/atypes.v
@@ -11,10 +11,8 @@
 // idx:  u16(type) & 0xffff
 module table
 
-import (
-	strings
-	v.ast
-)
+import strings
+import v.ast
 
 pub type Type int
 
@@ -28,6 +26,7 @@ mut:
 	kind       Kind
 	name       string
 	methods    []Fn
+	mod        string
 }
 
 pub enum TypeFlag {
@@ -310,7 +309,7 @@ pub fn (t TypeSymbol) str() string {
 	return t.name
 }
 */
-pub fn (t mut Table) register_builtin_type_symbols() {
+pub fn (var t Table) register_builtin_type_symbols() {
 	// reserve index 0 so nothing can go there
 	// save index check, 0 will mean not found
 	t.register_type_symbol(TypeSymbol{
@@ -527,7 +526,7 @@ pub fn (k Kind) str() string {
 }
 
 pub fn (kinds []Kind) str() string {
-	mut kinds_str := ''
+	var kinds_str := ''
 	for i, k in kinds {
 		kinds_str += k.str()
 		if i < kinds.len - 1 {
@@ -594,7 +593,7 @@ pub:
 pub fn (table &Table) type_to_str(t Type) string {
 	sym := table.get_type_symbol(t)
 	if sym.kind == .multi_return {
-		mut res := '('
+		var res := '('
 		mr_info := sym.info as MultiReturn
 		for i, typ in mr_info.types {
 			res += table.type_to_str(typ)
@@ -605,7 +604,7 @@ pub fn (table &Table) type_to_str(t Type) string {
 		res += ')'
 		return res
 	}
-	mut res := sym.name
+	var res := sym.name
 	if sym.kind == .array {
 		res = res.replace('array_', '[]')
 	} else if sym.kind == .map {
diff --git a/vlib/v/table/cflags.v b/vlib/v/table/cflags.v
index d0f1a73a4e..380e3266ab 100644
--- a/vlib/v/table/cflags.v
+++ b/vlib/v/table/cflags.v
@@ -17,15 +17,15 @@ fn (table &Table) has_cflag(cflag builder.CFlag) bool {
 
 // parse the flags to (table.cflags) []CFlag
 // Note: clean up big time (joe-c)
-fn (table mut Table) parse_cflag(cflag, mod string, ctimedefines []string) ?bool {
+pub fn (var table Table) parse_cflag(cflag, mod string, ctimedefines []string) ?bool {
 	allowed_flags := ['framework', 'library', 'Wa', 'Wl', 'Wp', 'I', 'l', 'L']
 	flag_orig := cflag.trim_space()
-	mut flag := flag_orig
+	var flag := flag_orig
 	if flag == '' {
 		return true
 	}
-	mut fos := ''
-	mut allowed_os_overrides := ['linux', 'darwin', 'freebsd', 'windows', 'mingw', 'solaris']
+	var fos := ''
+	var allowed_os_overrides := ['linux', 'darwin', 'freebsd', 'windows', 'mingw', 'solaris']
 	allowed_os_overrides << ctimedefines
 	for os_override in allowed_os_overrides {
 		if !flag.starts_with(os_override) {
@@ -37,9 +37,9 @@ fn (table mut Table) parse_cflag(cflag, mod string, ctimedefines []string) ?bool
 		fos = flag[..pos].trim_space()
 		flag = flag[pos..].trim_space()
 	}
-	for  {
-		mut name := ''
-		mut value := ''
+	for {
+		var name := ''
+		var value := ''
 		if flag[0] == `-` {
 			for f in allowed_flags {
 				i := 1 + f.len
@@ -50,11 +50,11 @@ fn (table mut Table) parse_cflag(cflag, mod string, ctimedefines []string) ?bool
 				}
 			}
 		}
-		mut index := flag.index(' -') or {
+		var index := flag.index(' -') or {
 			-1
 		}
 		for index > -1 {
-			mut has_next := false
+			var has_next := false
 			for f in allowed_flags {
 				i := index + 2 + f.len
 				if i <= flag.len && f == flag[index + 2..i] {
diff --git a/vlib/v/table/table.v b/vlib/v/table/table.v
index a04e4b084b..3d8d0a30f4 100644
--- a/vlib/v/table/table.v
+++ b/vlib/v/table/table.v
@@ -3,10 +3,8 @@
 // that can be found in the LICENSE file.
 module table
 
-import (
-	os
-	v.builder
-)
+import os
+import v.builder
 
 pub struct Table {
 pub mut:
@@ -25,8 +23,10 @@ pub:
 	return_type Type
 	is_variadic bool
 	is_c        bool
-	is_js		bool
+	is_js       bool
 	is_generic  bool
+	is_pub      bool
+	mod         string
 }
 
 pub struct Arg {
@@ -45,14 +45,14 @@ mut:
 }
 
 pub fn new_table() &Table {
-	mut t := &Table{}
+	var t := &Table{}
 	t.register_builtin_type_symbols()
 	return t
 }
 
 // used to compare fn's & for naming anon fn's
 pub fn (f &Fn) signature() string {
-	mut sig := ''
+	var sig := ''
 	for i, arg in f.args {
 		// TODO: for now ignore mut/pts in sig for now
 		typ := type_set_nr_muls(arg.typ, 0)
@@ -85,12 +85,12 @@ pub fn (t &Table) known_fn(name string) bool {
 	return true
 }
 
-pub fn (t mut Table) register_fn(new_fn Fn) {
+pub fn (var t Table) register_fn(new_fn Fn) {
 	// println('reg fn $new_fn.name nr_args=$new_fn.args.len')
 	t.fns[new_fn.name] = new_fn
 }
 
-pub fn (t mut TypeSymbol) register_method(new_fn Fn) {
+pub fn (var t TypeSymbol) register_method(new_fn Fn) {
 	t.methods << new_fn
 }
 
@@ -142,7 +142,7 @@ pub fn (t &Table) type_has_method(s &TypeSymbol, name string) bool {
 // search from current type up through each parent looking for method
 pub fn (t &Table) type_find_method(s &TypeSymbol, name string) ?Fn {
 	// println('type_find_method($s.name, $name) types.len=$t.types.len s.parent_idx=$s.parent_idx')
-	mut ts := s
+	var ts := s
 	for {
 		if method := ts.find_method(name) {
 			return method
@@ -166,7 +166,7 @@ pub fn (t &Table) struct_has_field(s &TypeSymbol, name string) bool {
 // search from current type up through each parent looking for field
 pub fn (t &Table) struct_find_field(s &TypeSymbol, name string) ?Field {
 	// println('struct_find_field($s.name, $name) types.len=$t.types.len s.parent_idx=$s.parent_idx')
-	mut ts := s
+	var ts := s
 	for {
 		if field := ts.find_field(name) {
 			return field
@@ -210,12 +210,11 @@ pub fn (t &Table) get_type_name(typ Type) string {
 	return typ_sym.name
 }
 
-
 // this will override or register builtin type
 // allows prexisitng types added in register_builtins
 // to be overriden with their real type info
 [inline]
-pub fn (t mut Table) register_builtin_type_symbol(typ TypeSymbol) int {
+pub fn (var t Table) register_builtin_type_symbol(typ TypeSymbol) int {
 	existing_idx := t.type_idxs[typ.name]
 	if existing_idx > 0 {
 		if existing_idx >= string_type_idx {
@@ -235,7 +234,7 @@ pub fn (t mut Table) register_builtin_type_symbol(typ TypeSymbol) int {
 }
 
 [inline]
-pub fn (t mut Table) register_type_symbol(typ TypeSymbol) int {
+pub fn (var t Table) register_type_symbol(typ TypeSymbol) int {
 	// println('register_type_symbol( $typ.name )')
 	existing_idx := t.type_idxs[typ.name]
 	if existing_idx > 0 {
@@ -309,7 +308,7 @@ pub fn (t &Table) map_name(key_type, value_type Type) string {
 	// return 'map_${value_type_sym.name}' + suffix
 }
 
-pub fn (t mut Table) find_or_register_map(key_type, value_type Type) int {
+pub fn (var t Table) find_or_register_map(key_type, value_type Type) int {
 	name := t.map_name(key_type, value_type)
 	// existing
 	existing_idx := t.type_idxs[name]
@@ -329,7 +328,7 @@ pub fn (t mut Table) find_or_register_map(key_type, value_type Type) int {
 	return t.register_type_symbol(map_typ)
 }
 
-pub fn (t mut Table) find_or_register_array(elem_type Type, nr_dims int) int {
+pub fn (var t Table) find_or_register_array(elem_type Type, nr_dims int) int {
 	name := t.array_name(elem_type, nr_dims)
 	// existing
 	existing_idx := t.type_idxs[name]
@@ -349,7 +348,7 @@ pub fn (t mut Table) find_or_register_array(elem_type Type, nr_dims int) int {
 	return t.register_type_symbol(array_type)
 }
 
-pub fn (t mut Table) find_or_register_array_fixed(elem_type Type, size, nr_dims int) int {
+pub fn (var t Table) find_or_register_array_fixed(elem_type Type, size, nr_dims int) int {
 	name := t.array_fixed_name(elem_type, size, nr_dims)
 	// existing
 	existing_idx := t.type_idxs[name]
@@ -369,8 +368,8 @@ pub fn (t mut Table) find_or_register_array_fixed(elem_type Type, size, nr_dims
 	return t.register_type_symbol(array_fixed_type)
 }
 
-pub fn (t mut Table) find_or_register_multi_return(mr_typs []Type) int {
-	mut name := 'multi_return'
+pub fn (var t Table) find_or_register_multi_return(mr_typs []Type) int {
+	var name := 'multi_return'
 	for mr_typ in mr_typs {
 		mr_type_sym := t.get_type_symbol(mr_typ)
 		name += '_$mr_type_sym.name'
@@ -391,7 +390,7 @@ pub fn (t mut Table) find_or_register_multi_return(mr_typs []Type) int {
 	return t.register_type_symbol(mr_type)
 }
 
-pub fn (t mut Table) find_or_register_fn_type(f Fn, has_decl bool) int {
+pub fn (var t Table) find_or_register_fn_type(f Fn, has_decl bool) int {
 	is_anon := f.name.len == 0
 	name := if is_anon { 'anon_fn_$f.signature()' } else { f.name }
 	return t.register_type_symbol(TypeSymbol{
@@ -405,7 +404,7 @@ pub fn (t mut Table) find_or_register_fn_type(f Fn, has_decl bool) int {
 	})
 }
 
-pub fn (t mut Table) add_placeholder_type(name string) int {
+pub fn (var t Table) add_placeholder_type(name string) int {
 	ph_type := TypeSymbol{
 		kind: .placeholder
 		name: name