diff --git a/vlib/v/builder/msvc.v b/vlib/v/builder/msvc.v
index e9754c879e..82a8e679f0 100644
--- a/vlib/v/builder/msvc.v
+++ b/vlib/v/builder/msvc.v
@@ -254,7 +254,8 @@ pub fn (mut v Builder) cc_msvc() {
 	// Not all of these are needed (but the compiler should discard them if they are not used)
 	// these are the defaults used by msbuild and visual studio
 	mut real_libs := ['kernel32.lib', 'user32.lib', 'advapi32.lib']
-	sflags := v.get_os_cflags().msvc_string_flags()
+	//sflags := v.get_os_cflags().msvc_string_flags()
+	sflags := msvc_string_flags(v.get_os_cflags())
 	real_libs << sflags.real_libs
 	inc_paths := sflags.inc_paths
 	lib_paths := sflags.lib_paths
@@ -359,7 +360,8 @@ mut:
 	other_flags []string
 }
 
-fn (cflags []cflag.CFlag) msvc_string_flags() MsvcStringFlags {
+//pub fn (cflags []CFlag) msvc_string_flags() MsvcStringFlags {
+pub fn msvc_string_flags(cflags []cflag.CFlag) MsvcStringFlags {
 	mut real_libs := []string{}
 	mut inc_paths := []string{}
 	mut lib_paths := []string{}
@@ -405,3 +407,4 @@ fn (cflags []cflag.CFlag) msvc_string_flags() MsvcStringFlags {
 		other_flags: other_flags
 	}
 }
+
diff --git a/vlib/v/cflag/cflags.v b/vlib/v/cflag/cflags.v
index ba53c8422b..9af675670c 100644
--- a/vlib/v/cflag/cflags.v
+++ b/vlib/v/cflag/cflags.v
@@ -32,15 +32,15 @@ pub fn (cf &CFlag) format() string {
 }
 
 // TODO: implement msvc specific c_options_before_target and c_options_after_target ...
-fn (cflags []CFlag) c_options_before_target_msvc() string {
+pub fn (cflags []CFlag) c_options_before_target_msvc() string {
 	return ''
 }
 
-fn (cflags []CFlag) c_options_after_target_msvc() string {
+pub fn (cflags []CFlag) c_options_after_target_msvc() string {
 	return ''
 }
 
-fn (cflags []CFlag) c_options_before_target() string {
+pub fn (cflags []CFlag) c_options_before_target() string {
 	// -I flags, optimization flags and so on
 	mut args := []string{}
 	for flag in cflags {
@@ -51,7 +51,7 @@ fn (cflags []CFlag) c_options_before_target() string {
 	return args.join(' ')
 }
 
-fn (cflags []CFlag) c_options_after_target() string {
+pub fn (cflags []CFlag) c_options_after_target() string {
 	// -l flags (libs)
 	mut args := []string{}
 	for flag in cflags {
@@ -62,7 +62,7 @@ fn (cflags []CFlag) c_options_after_target() string {
 	return args.join(' ')
 }
 
-fn (cflags []CFlag) c_options_without_object_files() string {
+pub fn (cflags []CFlag) c_options_without_object_files() string {
 	mut args := []string{}
 	for flag in cflags {
 		if flag.value.ends_with('.o') || flag.value.ends_with('.obj') {
@@ -73,7 +73,7 @@ fn (cflags []CFlag) c_options_without_object_files() string {
 	return args.join(' ')
 }
 
-fn (cflags []CFlag) c_options_only_object_files() string {
+pub fn (cflags []CFlag) c_options_only_object_files() string {
 	mut args := []string{}
 	for flag in cflags {
 		if flag.value.ends_with('.o') || flag.value.ends_with('.obj') {
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index e508e3ab61..65ac630414 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -731,7 +731,7 @@ pub fn (mut c Checker) call_method(mut call_expr ast.CallExpr) table.Type {
 				table.FnType { ret_type = it.func.return_type }
 				else { ret_type = arg_type }
 			}
-			call_expr.return_type = c.table.find_or_register_array(ret_type, 1)
+			call_expr.return_type = c.table.find_or_register_array(ret_type, 1, c.mod)
 		} else if method_name == 'clone' {
 			// need to return `array_xxx` instead of `array`
 			// in ['clone', 'str'] {
@@ -1415,7 +1415,8 @@ pub fn (mut c Checker) array_init(mut array_init ast.ArrayInit) table.Type {
 			idx := c.table.find_or_register_array_fixed(elem_type, array_init.exprs.len, 1)
 			array_init.typ = table.new_type(idx)
 		} else {
-			idx := c.table.find_or_register_array(elem_type, 1)
+			sym := c.table.get_type_symbol(elem_type)
+			idx := c.table.find_or_register_array(elem_type, 1, sym.mod)
 			array_init.typ = table.new_type(idx)
 		}
 		array_init.elem_type = elem_type
@@ -2268,7 +2269,7 @@ pub fn (mut c Checker) index_expr(mut node ast.IndexExpr) table.Type {
 		// fixed_array[1..2] => array
 		if typ_sym.kind == .array_fixed {
 			elem_type := c.table.value_type(typ)
-			idx := c.table.find_or_register_array(elem_type, 1)
+			idx := c.table.find_or_register_array(elem_type, 1, c.mod)
 			return table.new_type(idx)
 		}
 	}
@@ -2438,6 +2439,11 @@ fn (mut c Checker) fn_decl(it ast.FnDecl) {
 		// if sym.has_method(it.name) {
 		// c.warn('duplicate method `$it.name`', it.pos)
 		// }
+		// Do not allow to modify types from other modules
+		if sym.mod != c.mod && !c.is_builtin_mod && sym.mod != '' { // TODO remove != ''
+			c.warn('cannot define methods on types from other modules (' + 'current module is `$c.mod`, `$sym.name` is from `$sym.mod`)',
+				it.pos)
+		}
 	}
 	if it.language == .v {
 		// Make sure all types are valid
diff --git a/vlib/v/parser/containers.v b/vlib/v/parser/containers.v
index 70f32aee74..ac1ddfcb65 100644
--- a/vlib/v/parser/containers.v
+++ b/vlib/v/parser/containers.v
@@ -27,9 +27,10 @@ fn (mut p Parser) array_init() ast.ArrayInit {
 		if p.tok.kind in [.name, .amp] && p.tok.line_nr == line_nr {
 			elem_type_pos = p.tok.position()
 			elem_type = p.parse_type()
+			sym := p.table.get_type_symbol(elem_type)
 			// this is set here becasue its a known type, others could be the
 			// result of expr so we do those in checker
-			idx := p.table.find_or_register_array(elem_type, 1)
+			idx := p.table.find_or_register_array(elem_type, 1, sym.mod)
 			array_type = table.new_type(idx)
 			has_type = true
 		}
diff --git a/vlib/v/parser/fn.v b/vlib/v/parser/fn.v
index eb6ea874a5..67b26b8c46 100644
--- a/vlib/v/parser/fn.v
+++ b/vlib/v/parser/fn.v
@@ -159,10 +159,12 @@ fn (mut p Parser) fn_decl() ast.FnDecl {
 		// TODO: talk to alex, should mut be parsed with the type like this?
 		// or should it be a property of the arg, like this ptr/mut becomes indistinguishable
 		rec_type = p.parse_type_with_mut(rec_mut)
+		/*
 		sym := p.table.get_type_symbol(rec_type)
-		if sym.mod != p.mod && sym.mod != '' {
-			p.error('cannot define methods on types from other modules (current module is `$p.mod`, `$sym.name` is from `$sym.mod`)')
+		if sym.mod != p.mod { // && sym.mod != '' {
+			p.warn('cannot define methods on types from other modules (current module is `$p.mod`, `$sym.name` is from `$sym.mod`)')
 		}
+		*/
 		if is_amp && rec_mut {
 			p.error('use `(mut f Foo)` or `(f &Foo)` instead of `(mut f &Foo)`')
 		}
diff --git a/vlib/v/parser/parse_type.v b/vlib/v/parser/parse_type.v
index ef4036eb69..3ba8b3984c 100644
--- a/vlib/v/parser/parse_type.v
+++ b/vlib/v/parser/parse_type.v
@@ -13,6 +13,7 @@ pub fn (mut p Parser) parse_array_type() table.Type {
 		p.next()
 		p.check(.rsbr)
 		elem_type := p.parse_type()
+		//sym := p.table.get_type_symbol(elem_type)
 		idx := p.table.find_or_register_array_fixed(elem_type, size, 1)
 		return table.new_type(idx)
 	}
@@ -29,7 +30,8 @@ pub fn (mut p Parser) parse_array_type() table.Type {
 		p.check(.rsbr)
 		nr_dims++
 	}
-	idx := p.table.find_or_register_array(elem_type, nr_dims)
+	sym := p.table.get_type_symbol(elem_type)
+	idx := p.table.find_or_register_array(elem_type, nr_dims, sym.mod)
 	return table.new_type(idx)
 }
 
diff --git a/vlib/v/parser/struct.v b/vlib/v/parser/struct.v
index f83e50c4c8..bbe4049ee7 100644
--- a/vlib/v/parser/struct.v
+++ b/vlib/v/parser/struct.v
@@ -189,6 +189,7 @@ fn (mut p Parser) struct_decl() ast.StructDecl {
 		// with the real struct type info parsed from builtin
 		ret = p.table.register_builtin_type_symbol(t)
 	} else {
+		// println('reg type symbol $name mod=$p.mod')
 		ret = p.table.register_type_symbol(t)
 	}
 	if ret == -1 {
diff --git a/vlib/v/table/table.v b/vlib/v/table/table.v
index aed23c6013..b0a876c5d8 100644
--- a/vlib/v/table/table.v
+++ b/vlib/v/table/table.v
@@ -325,7 +325,7 @@ pub fn (mut t Table) find_or_register_map(key_type, value_type Type) int {
 	return t.register_type_symbol(map_typ)
 }
 
-pub fn (mut t Table) find_or_register_array(elem_type Type, nr_dims int) int {
+pub fn (mut t Table) find_or_register_array(elem_type Type, nr_dims int, mod string) int {
 	name := t.array_name(elem_type, nr_dims)
 	// existing
 	existing_idx := t.type_idxs[name]
@@ -341,6 +341,7 @@ pub fn (mut t Table) find_or_register_array(elem_type Type, nr_dims int) int {
 			elem_type: elem_type
 			nr_dims: nr_dims
 		}
+		mod: mod
 	}
 	return t.register_type_symbol(array_type)
 }