diff --git a/compiler/cc.v b/compiler/cc.v
index 37401ed3d6..21f4a1e301 100644
--- a/compiler/cc.v
+++ b/compiler/cc.v
@@ -64,17 +64,14 @@ fn (v mut V) cc() {
 	}
 	if v.pref.build_mode == .build_module {
 		// Create the modules & out directory if it's not there.
-		out_dir := '$v_modules_path${os.PathSeparator}$v.dir'
-		if !os.dir_exists(out_dir) {
-			// create recursive
-			mut mkpath := v_modules_path
-			for subdir in v.dir.split(os.PathSeparator) {
-				mkpath += os.PathSeparator + subdir
-				if !os.dir_exists(mkpath) {
-					os.mkdir(mkpath)
-				}
-			}
-			//os.mkdir(out_dir)
+		mut out_dir := if v.dir.starts_with('vlib') {
+			'$v_modules_path${os.PathSeparator}cache${os.PathSeparator}$v.dir'	
+		} else {
+			'$v_modules_path${os.PathSeparator}$v.dir'
+		}
+		pdir := out_dir.all_before_last(os.PathSeparator)
+		if !os.dir_exists(pdir) {
+			os.mkdir_all(pdir)
 		}
 		v.out_name = '${out_dir}.o' //v.out_name
 		println('Building ${v.out_name}...')
@@ -120,25 +117,25 @@ fn (v mut V) cc() {
 	}
 	else if v.pref.is_debug {
 		vexe := os.executable()
-		builtin_o_path := '$v_modules_path/cache/builtin.o'
+		builtin_o_path := '$v_modules_path${os.PathSeparator}cache${os.PathSeparator}vlib${os.PathSeparator}builtin.o'
 		if os.file_exists(builtin_o_path) {
 			libs = builtin_o_path
 		} else {
 			println('$builtin_o_path not found... building module builtin')
-			os.system('$vexe build module vlib/builtin')
+			os.system('$vexe build module vlib${os.PathSeparator}builtin')
 		}
 		for imp in v.table.imports {
 			if imp.contains('vweb') { continue } // not working
 			if imp == 'webview' { continue }
 			
 			imp_path := imp.replace('.', os.PathSeparator)
-			path := 	'$v_modules_path/cache/${imp_path}.o'
+			path := 	'$v_modules_path${os.PathSeparator}cache${os.PathSeparator}vlib${os.PathSeparator}${imp_path}.o'
 			println('adding ${imp_path}.o')
 			if os.file_exists(path) {
 				libs += ' ' + path
 			} else {
 				println('$path not found... building module $imp')
-				os.system('$vexe build module vlib/$imp_path')
+				os.system('$vexe build module vlib${os.PathSeparator}$imp_path')
 			}	
 		}
 	}
diff --git a/compiler/cheaders.v b/compiler/cheaders.v
index 4978d1d6b0..05a6a187f2 100644
--- a/compiler/cheaders.v
+++ b/compiler/cheaders.v
@@ -94,13 +94,6 @@ CommonCHeaders = '
 #define OPTION_CAST(x)
 #endif
 
-void pthread_mutex_lock(HANDLE *m) {
-	WaitForSingleObject(*m, INFINITE);
-}
-
-void pthread_mutex_unlock(HANDLE *m) {
-	ReleaseMutex(*m);
-}
 #else
 #include <pthread.h>
 #endif
diff --git a/compiler/live.v b/compiler/live.v
index 72d190d1f0..95abeb1413 100644
--- a/compiler/live.v
+++ b/compiler/live.v
@@ -131,6 +131,14 @@ int load_so(byteptr path) {
 		}
 		else {
 			cgen.genln('
+void pthread_mutex_lock(HANDLE *m) {
+	WaitForSingleObject(*m, INFINITE);
+}
+
+void pthread_mutex_unlock(HANDLE *m) {
+	ReleaseMutex(*m);
+}
+
 void* live_lib=0;
 int load_so(byteptr path) {
 	char cpath[1024];
diff --git a/compiler/main.v b/compiler/main.v
index d323365a5a..18aa5613a2 100644
--- a/compiler/main.v
+++ b/compiler/main.v
@@ -400,6 +400,9 @@ fn (v mut V) generate_init() {
 	if v.pref.build_mode == .default_mode {
 		mut call_mod_init := ''
 		mut call_mod_init_consts := ''
+		if 'builtin' in v.cached_mods {
+			call_mod_init_consts += 'builtin__init_consts();\n'
+		}
 		for mod in v.table.imports {
 			init_fn_name := mod_gen_name(mod) + '__init'
 			if v.table.known_fn(init_fn_name) {
@@ -610,8 +613,9 @@ fn (v &V) v_files_from_dir(dir string) []string {
 fn (v mut V) add_v_files_to_compile() {
 	mut builtin_files := v.get_builtin_files()
 	// Builtin cache exists? Use it.
-	builtin_vh := '$v_modules_path${os.PathSeparator}builtin.vh'
+	builtin_vh := '$v_modules_path${os.PathSeparator}vlib${os.PathSeparator}builtin.vh'
 	if v.pref.is_debug && os.file_exists(builtin_vh) {
+		v.cached_mods << 'builtin'
 		builtin_files = [builtin_vh]
 	}
 	// Parse builtin imports
@@ -653,7 +657,7 @@ fn (v mut V) add_v_files_to_compile() {
 		// use cached built module if exists
 		if v.pref.build_mode != .build_module && !mod.contains('vweb') {
 			mod_path := mod.replace('.', os.PathSeparator)
-			vh_path := '$v_modules_path/${mod_path}.vh'
+			vh_path := '$v_modules_path${os.PathSeparator}vlib${os.PathSeparator}${mod_path}.vh'
 			if v.pref.is_debug && os.file_exists(vh_path) {
 				println('using cached module `$mod`: $vh_path')
 				v.cached_mods << mod
@@ -822,6 +826,9 @@ fn new_v(args[]string) &V {
 	if dir.ends_with(os.PathSeparator) {
 		dir = dir.all_before_last(os.PathSeparator)
 	}
+	if dir.starts_with('.$os.PathSeparator') {
+		dir = dir.right(2)
+	}
 	adir := os.realpath(dir)
 	if args.len < 2 {
 		dir = ''
@@ -918,7 +925,7 @@ fn new_v(args[]string) &V {
 		println('Go to https://vlang.io to install V.')
 		exit(1)
 	}
-	//println('out_name:$out_name')
+	// println('out_name:$out_name')
 	mut out_name_c := os.realpath('${out_name}.tmp.c')
 
 	cflags := get_cmdline_cflags(args)
diff --git a/compiler/module_header.v b/compiler/module_header.v
index 9899a8c819..7dab622e2a 100644
--- a/compiler/module_header.v
+++ b/compiler/module_header.v
@@ -107,17 +107,15 @@ fn v_type_str(typ_ string) string {
 fn (v &V) generate_vh() {
 	println('\n\n\n\nGenerating a V header file for module `$v.mod`')
 	mod_path := v.mod.replace('.', os.PathSeparator)
-	dir := '$v_modules_path${os.PathSeparator}$mod_path'
+	dir := if v.dir.starts_with('vlib') {
+		'$v_modules_path${os.PathSeparator}$v.dir'
+	} else {
+		'$v_modules_path${os.PathSeparator}$mod_path'
+	}
 	path := dir + '.vh'
-	if !os.dir_exists(dir) {
-		// create recursive
-		mut mkpath := v_modules_path
-		for subdir in mod_path.split(os.PathSeparator) {
-			mkpath += os.PathSeparator + subdir
-			if !os.dir_exists(mkpath) {
-				os.mkdir(mkpath)
-			}
-		}
+	pdir := dir.all_before_last(os.PathSeparator)
+	if !os.dir_exists(pdir) {
+		os.mkdir_all(pdir)
 		// os.mkdir(os.realpath(dir))
 	}
 	file := os.create(path) or { panic(err) }
diff --git a/vlib/os/os.v b/vlib/os/os.v
index 5e5ef8fa83..56c1d3f8c2 100644
--- a/vlib/os/os.v
+++ b/vlib/os/os.v
@@ -859,12 +859,11 @@ pub fn print_backtrace() {
 }
 
 pub fn mkdir_all(path string) {
-	mut p := ''
+	mut p := if path.starts_with(os.PathSeparator) { os.PathSeparator } else { '' }
 	for subdir in path.split(os.PathSeparator) {
-		p += os.PathSeparator + subdir
+		p += subdir + os.PathSeparator
 		if !os.dir_exists(p) {
 			os.mkdir(p)
 		}
 	}
-}	
-
+}