diff --git a/.github/workflows/android_cross_compile.vsh b/.github/workflows/android_cross_compile.vsh
index 40526bca77..764d281f28 100755
--- a/.github/workflows/android_cross_compile.vsh
+++ b/.github/workflows/android_cross_compile.vsh
@@ -10,7 +10,7 @@ fn main() {
 	assert ndk.found()
 	assert vxt.found()
 
-	work_dir := os.join_path(os.temp_dir(), 'android_cross_compile_test')
+	work_dir := os.join_path(os.vtmp_dir(), 'android_cross_compile_test')
 	os.rm(work_dir) or {}
 	os.mkdir_all(work_dir) or { panic(err) }
 	vexe := vxt.vexe()
diff --git a/cmd/tools/modules/testing/common.v b/cmd/tools/modules/testing/common.v
index 74a3e13ec9..ddb1bc1c1e 100644
--- a/cmd/tools/modules/testing/common.v
+++ b/cmd/tools/modules/testing/common.v
@@ -597,9 +597,12 @@ pub fn header(msg string) {
 	flush_stdout()
 }
 
+// setup_new_vtmp_folder creates a new nested folder inside VTMP, then resets VTMP to it,
+// so that V programs/tests will write their temporary files to new location.
+// The new nested folder, and its contents, will get removed after all tests/programs succeed.
 pub fn setup_new_vtmp_folder() string {
 	now := time.sys_mono_now()
-	new_vtmp_dir := os.join_path(os.temp_dir(), 'v', 'tsession_${sync.thread_id().hex()}_$now')
+	new_vtmp_dir := os.join_path(os.vtmp_dir(), 'tsession_${sync.thread_id().hex()}_$now')
 	os.mkdir_all(new_vtmp_dir) or { panic(err) }
 	os.setenv('VTMP', new_vtmp_dir, true)
 	return new_vtmp_dir
diff --git a/cmd/tools/test_if_v_test_system_works.v b/cmd/tools/test_if_v_test_system_works.v
index 5af4ca8229..54cf8d00a5 100644
--- a/cmd/tools/test_if_v_test_system_works.v
+++ b/cmd/tools/test_if_v_test_system_works.v
@@ -26,7 +26,7 @@ fn get_vexe_path() string {
 }
 
 fn new_tdir() string {
-	dir := os.join_path(os.temp_dir(), 'v', rand.ulid())
+	dir := os.join_path(os.vtmp_dir(), 'v', rand.ulid())
 	os.rmdir_all(dir) or {}
 	os.mkdir_all(dir) or { panic(err) }
 	C.atexit(cleanup_tdir)
diff --git a/cmd/tools/vbump_test.v b/cmd/tools/vbump_test.v
index 15b81e61fa..e091b69358 100644
--- a/cmd/tools/vbump_test.v
+++ b/cmd/tools/vbump_test.v
@@ -2,7 +2,7 @@ import os
 
 const vexe = @VEXE
 
-const tfolder = os.join_path(os.temp_dir(), 'v', 'vbump')
+const tfolder = os.join_path(os.vtmp_dir(), 'v', 'vbump')
 
 fn testsuite_begin() {
 	os.mkdir_all(tfolder) or {}
diff --git a/cmd/tools/vcheck-md.v b/cmd/tools/vcheck-md.v
index 0227bf9b86..a114a289b2 100644
--- a/cmd/tools/vcheck-md.v
+++ b/cmd/tools/vcheck-md.v
@@ -21,7 +21,7 @@ const (
 	show_progress                  = os.getenv('GITHUB_JOB') == '' && '-silent' !in os.args
 	non_option_args                = cmdline.only_non_options(os.args[2..])
 	is_verbose                     = os.getenv('VERBOSE') != ''
-	vcheckfolder                   = os.join_path(os.temp_dir(), 'v', 'vcheck_$os.getuid()')
+	vcheckfolder                   = os.join_path(os.vtmp_dir(), 'v', 'vcheck_$os.getuid()')
 	should_autofix                 = os.getenv('VAUTOFIX') != ''
 	vexe                           = @VEXE
 )
diff --git a/cmd/tools/vcreate_test.v b/cmd/tools/vcreate_test.v
index 5e416b4c38..9ac4764992 100644
--- a/cmd/tools/vcreate_test.v
+++ b/cmd/tools/vcreate_test.v
@@ -1,6 +1,6 @@
 import os
 
-const test_path = os.join_path(os.temp_dir(), 'v', 'vcreate_test')
+const test_path = os.join_path(os.vtmp_dir(), 'v', 'vcreate_test')
 
 fn init_and_check() ! {
 	os.execute_or_exit('${os.quoted_path(@VEXE)} init')
diff --git a/cmd/tools/vfmt.v b/cmd/tools/vfmt.v
index eced1ea280..c78e85a5bb 100644
--- a/cmd/tools/vfmt.v
+++ b/cmd/tools/vfmt.v
@@ -33,7 +33,7 @@ mut:
 
 const (
 	formatted_file_token = '\@\@\@' + 'FORMATTED_FILE: '
-	vtmp_folder          = util.get_vtmp_folder()
+	vtmp_folder          = os.vtmp_dir()
 	term_colors          = term.can_show_color_on_stderr()
 )
 
diff --git a/cmd/tools/vgret.v b/cmd/tools/vgret.v
index eb4b32dcb5..e322665fd5 100644
--- a/cmd/tools/vgret.v
+++ b/cmd/tools/vgret.v
@@ -51,7 +51,7 @@ Examples:
   Compare screenshots in `/tmp/src` to existing screenshots in `/tmp/dst`
     v gret --compare-only /tmp/src /tmp/dst
 '
-	tmp_dir    = os.join_path(os.temp_dir(), 'v', tool_name)
+	tmp_dir    = os.join_path(os.vtmp_dir(), 'v', tool_name)
 	runtime_os = os.user_os()
 	v_root     = os.real_path(@VMODROOT)
 )
@@ -271,7 +271,7 @@ fn compare_screenshots(opt Options, output_path string, target_path string) ! {
 				if idiff_exe == '' {
 					return error('$tool_name need the `idiff` tool installed. It can be installed on Ubuntu with `sudo apt install openimageio-tools`')
 				}
-				diff_file := os.join_path(os.temp_dir(), os.file_name(src).all_before_last('.') +
+				diff_file := os.join_path(os.vtmp_dir(), os.file_name(src).all_before_last('.') +
 					'.diff.tif')
 				flags := app_config.compare.flags.join(' ')
 				diff_cmd := '${os.quoted_path(idiff_exe)} $flags -abs -od -o ${os.quoted_path(diff_file)} -abs ${os.quoted_path(src)} ${os.quoted_path(target)}'
@@ -305,18 +305,18 @@ fn compare_screenshots(opt Options, output_path string, target_path string) ! {
 			eprintln('$fail_src != $fail_target')
 		}
 		first := fails.keys()[0]
-		fail_copy := os.join_path(os.temp_dir(), 'fail.' + first.all_after_last('.'))
+		fail_copy := os.join_path(os.vtmp_dir(), 'fail.' + first.all_after_last('.'))
 		os.cp(first, fail_copy)!
 		eprintln('First failed file `$first` is copied to `$fail_copy`')
 
-		diff_file := os.join_path(os.temp_dir(), os.file_name(first).all_before_last('.') +
+		diff_file := os.join_path(os.vtmp_dir(), os.file_name(first).all_before_last('.') +
 			'.diff.tif')
-		diff_copy := os.join_path(os.temp_dir(), 'diff.tif')
+		diff_copy := os.join_path(os.vtmp_dir(), 'diff.tif')
 		if os.is_file(diff_file) {
 			os.cp(diff_file, diff_copy)!
 			eprintln('First failed diff file `$diff_file` is copied to `$diff_copy`')
 			eprintln('Removing alpha channel from $diff_copy ...')
-			final_fail_result_file := os.join_path(os.temp_dir(), 'diff.png')
+			final_fail_result_file := os.join_path(os.vtmp_dir(), 'diff.png')
 			opt.verbose_execute('convert ${os.quoted_path(diff_copy)} -alpha off ${os.quoted_path(final_fail_result_file)}')
 			eprintln('Final diff file: `$final_fail_result_file`')
 		}
diff --git a/cmd/tools/vrepl.v b/cmd/tools/vrepl.v
index 46edf4967b..0dbb921593 100644
--- a/cmd/tools/vrepl.v
+++ b/cmd/tools/vrepl.v
@@ -35,7 +35,7 @@ const (
 	is_stdin_a_pipe = os.is_atty(0) == 0
 	vexe            = os.getenv('VEXE')
 	vstartup        = os.getenv('VSTARTUP')
-	repl_folder     = os.join_path(os.temp_dir(), 'v', 'repl')
+	repl_folder     = os.join_path(os.vtmp_dir(), 'v', 'repl')
 )
 
 enum FnType {
diff --git a/cmd/tools/vsymlink.v b/cmd/tools/vsymlink.v
index 3d14db0389..5ebc2fb45a 100644
--- a/cmd/tools/vsymlink.v
+++ b/cmd/tools/vsymlink.v
@@ -1,6 +1,5 @@
 import os
 import v.pref
-import v.util
 
 $if windows {
 	$if tinyc {
@@ -32,7 +31,7 @@ fn main() {
 }
 
 fn cleanup_vtmp_folder() {
-	os.rmdir_all(util.get_vtmp_folder()) or {}
+	os.rmdir_all(os.vtmp_dir()) or {}
 }
 
 fn setup_symlink_github() {
diff --git a/cmd/tools/vwipe-cache.v b/cmd/tools/vwipe-cache.v
index cc4660ac31..4ce4ce848a 100644
--- a/cmd/tools/vwipe-cache.v
+++ b/cmd/tools/vwipe-cache.v
@@ -2,12 +2,10 @@ module main
 
 import os
 import v.vcache
-import v.util
 
 fn main() {
 	wipe_path(vcache.new_cache_manager([]).basepath, 'V cache')
-	wipe_path(util.get_vtmp_folder(), 'V tmp.c')
-	wipe_path(os.join_path(os.temp_dir(), 'v'), 'V tests')
+	wipe_path(os.vtmp_dir(), 'V tmp.c and tests folder')
 }
 
 fn wipe_path(cpath string, label string) {
diff --git a/vlib/io/util/util_test.v b/vlib/io/util/util_test.v
index 261afb3f50..df9fdc063a 100644
--- a/vlib/io/util/util_test.v
+++ b/vlib/io/util/util_test.v
@@ -5,7 +5,7 @@ const (
 	// tfolder will contain all the temporary files/subfolders made by
 	// the different tests. It would be removed in testsuite_end(), so
 	// individual os tests do not need to clean up after themselves.
-	tfolder = os.join_path(os.temp_dir(), 'v', 'tests', 'io_util_test')
+	tfolder = os.join_path(os.vtmp_dir(), 'v', 'tests', 'io_util_test')
 )
 
 fn testsuite_begin() {
diff --git a/vlib/net/unix/unix_test.v b/vlib/net/unix/unix_test.v
index 0813cb9959..547f810434 100644
--- a/vlib/net/unix/unix_test.v
+++ b/vlib/net/unix/unix_test.v
@@ -1,7 +1,7 @@
 import os
 import net.unix
 
-const tfolder = os.join_path(os.temp_dir(), 'v', 'unix_test')
+const tfolder = os.join_path(os.vtmp_dir(), 'v', 'unix_test')
 
 const test_port = os.join_path(tfolder, 'unix_domain_socket')
 
diff --git a/vlib/net/unix/use_net_and_net_unix_together_test.v b/vlib/net/unix/use_net_and_net_unix_together_test.v
index 85f277d34d..5ff7a8ba53 100644
--- a/vlib/net/unix/use_net_and_net_unix_together_test.v
+++ b/vlib/net/unix/use_net_and_net_unix_together_test.v
@@ -5,7 +5,7 @@ import net
 // ensure that `net` is used, i.e. no warnings
 const use_net = net.no_timeout
 
-const tfolder = os.join_path(os.temp_dir(), 'v', 'net_and_unix_together')
+const tfolder = os.join_path(os.vtmp_dir(), 'v', 'net_and_unix_together')
 
 const test_port = os.join_path(tfolder, 'unix_domain_socket')
 
diff --git a/vlib/orm/orm_sql_or_blocks_test.v b/vlib/orm/orm_sql_or_blocks_test.v
index 4c4fa5250a..f0d349e0db 100644
--- a/vlib/orm/orm_sql_or_blocks_test.v
+++ b/vlib/orm/orm_sql_or_blocks_test.v
@@ -6,7 +6,7 @@ struct User {
 	name string [unique]
 }
 
-const db_folder = os.join_path(os.temp_dir(), 'v', 'orm_sql')
+const db_folder = os.join_path(os.vtmp_dir(), 'v', 'orm_sql')
 
 const db_path = os.join_path(db_folder, 'sql_statement_or_blocks.db')
 
diff --git a/vlib/os/file_test.v b/vlib/os/file_test.v
index 7746a1e829..8da14b71af 100644
--- a/vlib/os/file_test.v
+++ b/vlib/os/file_test.v
@@ -1,6 +1,6 @@
 import os
 
-const tfolder = os.join_path(os.temp_dir(), 'v', 'tests', 'os_file_test')
+const tfolder = os.join_path(os.vtmp_dir(), 'v', 'tests', 'os_file_test')
 
 const tfile = os.join_path_single(tfolder, 'test_file')
 
diff --git a/vlib/os/find_abs_path_of_executable_test.v b/vlib/os/find_abs_path_of_executable_test.v
index 495ef51df6..334b0fc543 100644
--- a/vlib/os/find_abs_path_of_executable_test.v
+++ b/vlib/os/find_abs_path_of_executable_test.v
@@ -1,46 +1,46 @@
-module os
+import os
 
 fn test_find_abs_path_of_executable() {
-	tfolder := join_path(temp_dir(), 'v', 'tests', 'filepath_test')
-	rmdir_all(tfolder) or {}
-	assert !is_dir(tfolder)
-	mkdir_all(tfolder)?
+	tfolder := os.join_path(os.vtmp_dir(), 'v', 'tests', 'filepath_test')
+	os.rmdir_all(tfolder) or {}
+	assert !os.is_dir(tfolder)
+	os.mkdir_all(tfolder)!
 	defer {
-		rmdir_all(tfolder) or {}
+		os.rmdir_all(tfolder) or {}
 	}
 	//
-	original_path := getenv('PATH')
-	original_wdir := getwd()
+	original_path := os.getenv('PATH')
+	original_wdir := os.getwd()
 	defer {
-		chdir(original_wdir) or {}
+		os.chdir(original_wdir) or {}
 	}
 	//
-	new_path := tfolder + path_delimiter + original_path
-	setenv('PATH', new_path, true)
+	new_path := tfolder + os.path_delimiter + original_path
+	os.setenv('PATH', new_path, true)
 	//
 	mut myclang_file := 'myclang'
 	$if windows {
 		myclang_file += '.bat'
 	}
 	//
-	chdir(tfolder)?
-	write_file(myclang_file, 'echo hello')?
-	chmod(myclang_file, 0o0777)!
-	dump(real_path(myclang_file))
-	dump(is_executable(myclang_file))
+	os.chdir(tfolder)!
+	os.write_file(myclang_file, 'echo hello')!
+	os.chmod(myclang_file, 0o0777)!
+	dump(os.real_path(myclang_file))
+	dump(os.is_executable(myclang_file))
 	defer {
-		rm(myclang_file) or {}
+		os.rm(myclang_file) or {}
 	}
 	//
-	fpath := find_abs_path_of_executable('myclang') or {
+	fpath := os.find_abs_path_of_executable('myclang') or {
 		assert false
 		return
 	}
 	dump(fpath)
 	//
-	setenv('PATH', original_path, true)
-	chdir(home_dir())! // change to a *completely* different folder, to avoid the original PATH containing `.`
-	if x := find_abs_path_of_executable('myclang') {
+	os.setenv('PATH', original_path, true)
+	os.chdir(os.home_dir())! // change to a *completely* different folder, to avoid the original PATH containing `.`
+	if x := os.find_abs_path_of_executable('myclang') {
 		eprintln('> find_abs_path_of_executable should have failed, but instead it found: $x')
 		assert false
 	}
diff --git a/vlib/os/inode.c.v b/vlib/os/inode.c.v
index 0c8296c320..a82086416f 100644
--- a/vlib/os/inode.c.v
+++ b/vlib/os/inode.c.v
@@ -3,7 +3,7 @@
 // that can be found in the LICENSE file.
 module os
 
-enum FileType {
+pub enum FileType {
 	regular
 	directory
 	character_device
diff --git a/vlib/os/inode_test.v b/vlib/os/inode_test.v
index eaa31852bc..4bb1093b79 100644
--- a/vlib/os/inode_test.v
+++ b/vlib/os/inode_test.v
@@ -1,56 +1,56 @@
-module os
+import os
 
 const (
 	// tfolder will contain all the temporary files/subfolders made by
 	// the different tests. It would be removed in testsuite_end(), so
 	// individual os tests do not need to clean up after themselves.
-	tfolder = join_path(temp_dir(), 'v', 'tests', 'inode_test')
+	tfolder = os.join_path(os.vtmp_dir(), 'v', 'tests', 'inode_test')
 )
 
 fn testsuite_begin() {
-	eprintln('testsuite_begin, tfolder = $os.tfolder')
-	rmdir_all(os.tfolder) or {}
-	assert !is_dir(os.tfolder)
-	mkdir_all(os.tfolder) or { panic(err) }
-	chdir(os.tfolder) or {}
-	assert is_dir(os.tfolder)
+	eprintln('testsuite_begin, tfolder = $tfolder')
+	os.rmdir_all(tfolder) or {}
+	assert !os.is_dir(tfolder)
+	os.mkdir_all(tfolder) or { panic(err) }
+	os.chdir(tfolder) or {}
+	assert os.is_dir(tfolder)
 }
 
 fn testsuite_end() {
-	chdir(wd_at_startup) or {}
-	rmdir_all(os.tfolder) or { panic(err) }
-	assert !is_dir(os.tfolder)
+	os.chdir(os.wd_at_startup) or {}
+	os.rmdir_all(tfolder) or { panic(err) }
+	assert !os.is_dir(tfolder)
 }
 
 fn test_inode_file_type() {
 	filename := './test1.txt'
-	mut file := open_file(filename, 'w', 0o600) or { return }
+	mut file := os.open_file(filename, 'w', 0o600) or { return }
 	file.close()
-	mode := inode(filename)
-	rm(filename) or { panic(err) }
+	mode := os.inode(filename)
+	os.rm(filename) or { panic(err) }
 	assert mode.typ == .regular
 }
 
 fn test_inode_file_owner_permission() {
 	filename := './test2.txt'
-	mut file := open_file(filename, 'w', 0o600) or { return }
+	mut file := os.open_file(filename, 'w', 0o600) or { return }
 	file.close()
-	mode := inode(filename)
-	rm(filename) or {}
+	mode := os.inode(filename)
+	os.rm(filename) or {}
 	assert mode.owner.read
 	assert mode.owner.write
 	assert !mode.owner.execute
 }
 
 fn test_inode_file_permissions_bitmask() {
-	if user_os() == 'windows' {
+	if os.user_os() == 'windows' {
 		println('> skipping ${@FN} on windows')
 		return
 	}
 	filename := './test3.txt'
-	mut file := open_file(filename, 'w', 0o641) or { return }
+	mut file := os.open_file(filename, 'w', 0o641) or { return }
 	file.close()
-	mode := inode(filename)
-	rm(filename) or {}
+	mode := os.inode(filename)
+	os.rm(filename) or {}
 	assert mode.bitmask() == 0o641
 }
diff --git a/vlib/os/os.v b/vlib/os/os.v
index 6bac8af978..d24f524181 100644
--- a/vlib/os/os.v
+++ b/vlib/os/os.v
@@ -719,6 +719,23 @@ pub fn temp_dir() string {
 	return path
 }
 
+// vtmp_dir returns the path to a folder, that is writable to V programs, *and* specific
+// to the OS user. It can be overriden by setting the env variable `VTMP`.
+pub fn vtmp_dir() string {
+	mut vtmp := getenv('VTMP')
+	if vtmp.len > 0 {
+		return vtmp
+	}
+	uid := getuid()
+	vtmp = join_path_single(temp_dir(), 'v_$uid')
+	if !exists(vtmp) || !is_dir(vtmp) {
+		// create a new directory, that is private to the user:
+		mkdir_all(vtmp, mode: 0o700) or { panic(err) }
+	}
+	setenv('VTMP', vtmp, true)
+	return vtmp
+}
+
 fn default_vmodules_path() string {
 	hdir := home_dir()
 	res := join_path_single(hdir, '.vmodules')
diff --git a/vlib/os/os_test.v b/vlib/os/os_test.v
index 668ef27af1..a37bec6214 100644
--- a/vlib/os/os_test.v
+++ b/vlib/os/os_test.v
@@ -5,7 +5,7 @@ const (
 	// tfolder will contain all the temporary files/subfolders made by
 	// the different tests. It would be removed in testsuite_end(), so
 	// individual os tests do not need to clean up after themselves.
-	tfolder = os.join_path(os.temp_dir(), 'v', 'tests', 'os_test')
+	tfolder = os.join_path(os.vtmp_dir(), 'v', 'tests', 'os_test')
 )
 
 // os.args has to be *already initialized* with the program's argc/argv at this point
diff --git a/vlib/os/process_test.v b/vlib/os/process_test.v
index 8a44f5d4f7..7c45b75f21 100644
--- a/vlib/os/process_test.v
+++ b/vlib/os/process_test.v
@@ -6,7 +6,7 @@ import time
 const (
 	vexe                   = os.getenv('VEXE')
 	vroot                  = os.dir(vexe)
-	tfolder                = os.join_path(os.temp_dir(), 'v', 'tests', 'os_process')
+	tfolder                = os.join_path(os.vtmp_dir(), 'v', 'tests', 'os_process')
 	test_os_process        = os.join_path(tfolder, 'test_os_process.exe')
 	test_os_process_source = os.join_path(vroot, 'cmd/tools/test_os_process.v')
 )
diff --git a/vlib/stbi/stbi_test.v b/vlib/stbi/stbi_test.v
index e9fe1ef2c5..55933aea51 100644
--- a/vlib/stbi/stbi_test.v
+++ b/vlib/stbi/stbi_test.v
@@ -1,7 +1,7 @@
 import os
 import stbi
 
-const tfolder = os.join_path(os.temp_dir(), 'v', 'stbi')
+const tfolder = os.join_path(os.vtmp_dir(), 'v', 'stbi')
 
 fn testsuite_begin() {
 	os.mkdir_all(tfolder) or {}
diff --git a/vlib/toml/tests/alexcrichton.toml-rs-tests_test.v b/vlib/toml/tests/alexcrichton.toml-rs-tests_test.v
index abd899dc19..c19501e755 100644
--- a/vlib/toml/tests/alexcrichton.toml-rs-tests_test.v
+++ b/vlib/toml/tests/alexcrichton.toml-rs-tests_test.v
@@ -37,7 +37,7 @@ const (
 	]
 	tests_folder           = os.join_path('test-suite', 'tests')
 	jq                     = os.find_abs_path_of_executable('jq') or { '' }
-	compare_work_dir_root  = os.join_path(os.temp_dir(), 'v', 'toml', 'alexcrichton')
+	compare_work_dir_root  = os.join_path(os.vtmp_dir(), 'v', 'toml', 'alexcrichton')
 	// From: https://stackoverflow.com/a/38266731/1904615
 	jq_normalize           = r'# Apply f to composite entities recursively using keys[], and to atoms
 def sorted_walk(f):
diff --git a/vlib/toml/tests/burntsushi.toml-test_test.v b/vlib/toml/tests/burntsushi.toml-test_test.v
index b066be6117..931563adb6 100644
--- a/vlib/toml/tests/burntsushi.toml-test_test.v
+++ b/vlib/toml/tests/burntsushi.toml-test_test.v
@@ -27,7 +27,7 @@ const (
 	//'integer/long.toml', // TODO https://github.com/vlang/v/issues/9507
 
 	jq                     = os.find_abs_path_of_executable('jq') or { '' }
-	compare_work_dir_root  = os.join_path(os.temp_dir(), 'v', 'toml', 'burntsushi')
+	compare_work_dir_root  = os.join_path(os.vtmp_dir(), 'v', 'toml', 'burntsushi')
 	// From: https://stackoverflow.com/a/38266731/1904615
 	jq_normalize           = r'# Apply f to composite entities recursively using keys[], and to atoms
 def sorted_walk(f):
diff --git a/vlib/toml/tests/iarna.toml-spec-tests_test.v b/vlib/toml/tests/iarna.toml-spec-tests_test.v
index 5541914c31..b06e92cf19 100644
--- a/vlib/toml/tests/iarna.toml-spec-tests_test.v
+++ b/vlib/toml/tests/iarna.toml-spec-tests_test.v
@@ -43,7 +43,7 @@ const (
 
 	jq                     = os.find_abs_path_of_executable('jq') or { '' }
 	python                 = os.find_abs_path_of_executable('python') or { '' }
-	compare_work_dir_root  = os.join_path(os.temp_dir(), 'v', 'toml', 'iarna')
+	compare_work_dir_root  = os.join_path(os.vtmp_dir(), 'v', 'toml', 'iarna')
 	// From: https://stackoverflow.com/a/38266731/1904615
 	jq_normalize           = r'# Apply f to composite entities recursively using keys[], and to atoms
 def sorted_walk(f):
diff --git a/vlib/toml/tests/toml_test.v b/vlib/toml/tests/toml_test.v
index d31e923840..371cdbef53 100644
--- a/vlib/toml/tests/toml_test.v
+++ b/vlib/toml/tests/toml_test.v
@@ -68,7 +68,7 @@ fn test_toml() {
 }
 
 fn test_toml_file() {
-	out_path := os.join_path(os.temp_dir(), 'v', 'toml_tests')
+	out_path := os.join_path(os.vtmp_dir(), 'v', 'toml_tests')
 	test_file := os.join_path(out_path, 'toml_example.toml')
 	os.mkdir_all(out_path) or { assert false }
 	defer {
diff --git a/vlib/v/builder/builder_test.v b/vlib/v/builder/builder_test.v
index 43d22eec73..ab392686dc 100644
--- a/vlib/v/builder/builder_test.v
+++ b/vlib/v/builder/builder_test.v
@@ -2,7 +2,7 @@ module main
 
 import os
 
-const test_path = os.join_path(os.temp_dir(), 'v', 'run_check')
+const test_path = os.join_path(os.vtmp_dir(), 'v', 'run_check')
 
 const vexe = @VEXE
 
diff --git a/vlib/v/builder/interpreterbuilder/v_interpret_test.v b/vlib/v/builder/interpreterbuilder/v_interpret_test.v
index ca6b8c2b31..e647832cc2 100644
--- a/vlib/v/builder/interpreterbuilder/v_interpret_test.v
+++ b/vlib/v/builder/interpreterbuilder/v_interpret_test.v
@@ -9,7 +9,7 @@ fn interpreter_wrap(a string) string {
 }
 
 fn interp_test(expression string, expected string) ! {
-	tmpdir := os.join_path(os.temp_dir(), 'v', 'interpret_test_$rand.ulid()')
+	tmpdir := os.join_path(os.vtmp_dir(), 'v', 'interpret_test_$rand.ulid()')
 	os.mkdir_all(tmpdir) or {}
 	defer {
 		os.rmdir_all(tmpdir) or {}
diff --git a/vlib/v/builder/rebuilding.v b/vlib/v/builder/rebuilding.v
index addbb43132..fecd0571e9 100644
--- a/vlib/v/builder/rebuilding.v
+++ b/vlib/v/builder/rebuilding.v
@@ -358,7 +358,7 @@ pub fn (mut b Builder) rebuild(backend_cb FnBackend) {
 }
 
 pub fn (mut b Builder) get_vtmp_filename(base_file_name string, postfix string) string {
-	vtmp := util.get_vtmp_folder()
+	vtmp := os.vtmp_dir()
 	mut uniq := ''
 	if !b.pref.reuse_tmpc {
 		uniq = '.$rand.u64()'
diff --git a/vlib/v/gen/c/coutput_test.v b/vlib/v/gen/c/coutput_test.v
index c86c1f992c..e3a6f47d2c 100644
--- a/vlib/v/gen/c/coutput_test.v
+++ b/vlib/v/gen/c/coutput_test.v
@@ -21,7 +21,7 @@ fn mm(s string) string {
 fn test_out_files() {
 	println(term.colorize(term.green, '> testing whether .out files match:'))
 	os.chdir(vroot) or {}
-	output_path := os.join_path(os.temp_dir(), 'v', 'coutput', 'out')
+	output_path := os.join_path(os.vtmp_dir(), 'v', 'coutput', 'out')
 	os.mkdir_all(output_path)!
 	defer {
 		os.rmdir_all(output_path) or {}
@@ -92,7 +92,7 @@ fn test_out_files() {
 fn test_c_must_have_files() {
 	println(term.colorize(term.green, '> testing whether `.c.must_have` files match:'))
 	os.chdir(vroot) or {}
-	output_path := os.join_path(os.temp_dir(), 'v', 'coutput', 'c_must_have')
+	output_path := os.join_path(os.vtmp_dir(), 'v', 'coutput', 'c_must_have')
 	os.mkdir_all(output_path)!
 	defer {
 		os.rmdir_all(output_path) or {}
diff --git a/vlib/v/gen/golang/tests/golang_test.v b/vlib/v/gen/golang/tests/golang_test.v
index db577021b1..dfda3b7c13 100644
--- a/vlib/v/gen/golang/tests/golang_test.v
+++ b/vlib/v/gen/golang/tests/golang_test.v
@@ -19,7 +19,7 @@ fn test_golang() {
 	dir := os.join_path(vroot, 'vlib/v/gen/golang/tests')
 	files := os.ls(dir) or { panic(err) }
 	//
-	wrkdir := os.join_path(os.temp_dir(), 'v', 'tests', 'golang')
+	wrkdir := os.join_path(os.vtmp_dir(), 'v', 'tests', 'golang')
 	os.mkdir_all(wrkdir) or { panic(err) }
 	defer {
 		os.rmdir_all(wrkdir) or {}
diff --git a/vlib/v/gen/js/jsgen_test.v b/vlib/v/gen/js/jsgen_test.v
index 70ef00dab8..15ec1d9cf4 100644
--- a/vlib/v/gen/js/jsgen_test.v
+++ b/vlib/v/gen/js/jsgen_test.v
@@ -2,7 +2,7 @@ import os
 
 const (
 	test_dir     = os.join_path('vlib', 'v', 'gen', 'js', 'tests')
-	output_dir   = os.join_path(os.temp_dir(), 'v', '_js_tests/')
+	output_dir   = os.join_path(os.vtmp_dir(), 'v', '_js_tests/')
 	v_options    = '-b js -w'
 	node_options = ''
 )
diff --git a/vlib/v/gen/native/tests/native_test.v b/vlib/v/gen/native/tests/native_test.v
index 649858b36a..b99cc572fd 100644
--- a/vlib/v/gen/native/tests/native_test.v
+++ b/vlib/v/gen/native/tests/native_test.v
@@ -20,7 +20,7 @@ fn test_native() {
 	dir := os.join_path(vroot, 'vlib/v/gen/native/tests')
 	files := os.ls(dir) or { panic(err) }
 	//
-	wrkdir := os.join_path(os.temp_dir(), 'v', 'tests', 'native')
+	wrkdir := os.join_path(os.vtmp_dir(), 'v', 'tests', 'native')
 	os.mkdir_all(wrkdir) or { panic(err) }
 	defer {
 		os.rmdir_all(wrkdir) or {}
diff --git a/vlib/v/live/live_test.v b/vlib/v/live/live_test.v
index fd878a25a7..a48c1ee4f1 100644
--- a/vlib/v/live/live_test.v
+++ b/vlib/v/live/live_test.v
@@ -33,7 +33,7 @@ TODO: Cleanup this when/if v has better process control/communication primitives
 */
 const (
 	vexe                = os.getenv('VEXE')
-	vtmp_folder         = os.join_path(os.temp_dir(), 'v', 'tests', 'live')
+	vtmp_folder         = os.join_path(os.vtmp_dir(), 'v', 'tests', 'live')
 	tmp_file            = os.join_path(vtmp_folder, 'generated_live_program.tmp.v')
 	source_file         = os.join_path(vtmp_folder, 'generated_live_program.v')
 	genexe_file         = os.join_path(vtmp_folder, 'generated_live_program')
diff --git a/vlib/v/pkgconfig/bin/pkgconfig_test.v b/vlib/v/pkgconfig/bin/pkgconfig_test.v
index 7b58f15d6e..c8fe35fb1e 100644
--- a/vlib/v/pkgconfig/bin/pkgconfig_test.v
+++ b/vlib/v/pkgconfig/bin/pkgconfig_test.v
@@ -5,7 +5,7 @@ const vexe = os.getenv('VEXE')
 const vroot = os.dir(vexe)
 
 fn test_pkgconfig_can_be_compiled() {
-	tmp_exe := os.join_path(os.temp_dir(), '${os.getpid()}_pkgconfig.exe')
+	tmp_exe := os.join_path(os.vtmp_dir(), '${os.getpid()}_pkgconfig.exe')
 	pkgconfig_v_file := os.real_path(os.join_path(vroot, 'vlib/v/pkgconfig/bin/pkgconfig.v'))
 	assert !os.exists(tmp_exe)
 	res := os.system('${os.quoted_path(vexe)} -o ${os.quoted_path(tmp_exe)} ${os.quoted_path(pkgconfig_v_file)}')
@@ -13,5 +13,5 @@ fn test_pkgconfig_can_be_compiled() {
 		assert false
 	}
 	assert os.exists(tmp_exe)
-	os.rm(tmp_exe)?
+	os.rm(tmp_exe)!
 }
diff --git a/vlib/v/pref/options_test.v b/vlib/v/pref/options_test.v
index 04ecc3d03e..6a32ba80bb 100644
--- a/vlib/v/pref/options_test.v
+++ b/vlib/v/pref/options_test.v
@@ -5,7 +5,7 @@ import time
 
 const vexe = @VEXE
 
-const tfolder = os.join_path(os.temp_dir(), 'v', 'custom_compile')
+const tfolder = os.join_path(os.vtmp_dir(), 'v', 'custom_compile')
 
 fn testsuite_begin() {
 	os.mkdir_all(tfolder) or {}
diff --git a/vlib/v/tests/closure_generator_test.v b/vlib/v/tests/closure_generator_test.v
index b0ca7f9acb..09ed320f65 100644
--- a/vlib/v/tests/closure_generator_test.v
+++ b/vlib/v/tests/closure_generator_test.v
@@ -162,7 +162,7 @@ fn test_closure_return_${styp}_${i}() ? {
 
 	code := v_code.str()
 	println('Compiling V code (${code.count('\n')} lines) ...')
-	wrkdir := os.join_path(os.temp_dir(), 'v', 'tests', 'closures')
+	wrkdir := os.join_path(os.vtmp_dir(), 'v', 'tests', 'closures')
 	os.mkdir_all(wrkdir)?
 	os.chdir(wrkdir)?
 	os.write_file('closure_return_test.v', code)?
diff --git a/vlib/v/tests/crun_mode/crun_test.v b/vlib/v/tests/crun_mode/crun_test.v
index 728eb192f0..0b3703c71d 100644
--- a/vlib/v/tests/crun_mode/crun_test.v
+++ b/vlib/v/tests/crun_mode/crun_test.v
@@ -1,7 +1,7 @@
 import os
 import time
 
-const crun_folder = os.join_path(os.temp_dir(), 'v', 'crun_folder')
+const crun_folder = os.join_path(os.vtmp_dir(), 'v', 'crun_folder')
 
 const vprogram_file = os.join_path(crun_folder, 'vprogram.vv')
 
diff --git a/vlib/v/tests/run_v_code_from_stdin_test.v b/vlib/v/tests/run_v_code_from_stdin_test.v
index 7ec16d653a..c0c2414c56 100644
--- a/vlib/v/tests/run_v_code_from_stdin_test.v
+++ b/vlib/v/tests/run_v_code_from_stdin_test.v
@@ -4,13 +4,13 @@ const vexe = os.getenv('VEXE')
 
 const turn_off_vcolors = os.setenv('VCOLORS', 'never', true)
 
-const vtmp_folder = os.join_path(os.temp_dir(), 'v', 'tests', 'run_v_code')
+const vtmp_folder = os.join_path(os.vtmp_dir(), 'v', 'tests', 'run_v_code')
 
 fn test_vexe_is_set() {
 	assert vexe != ''
 }
 
-fn pipe_to_v_run() ? {
+fn pipe_to_v_run() ! {
 	os.mkdir_all(vtmp_folder) or {}
 	defer {
 		os.rmdir_all(vtmp_folder) or {}
@@ -18,7 +18,7 @@ fn pipe_to_v_run() ? {
 	cat_cmd := if os.user_os() == 'windows' { 'cmd /c type' } else { 'cat' }
 	tmp_v_file := os.join_path(os.real_path(vtmp_folder), 'generated_piped_program.v')
 	// eprintln('>>> tmp_v_file: $tmp_v_file')
-	os.write_file(tmp_v_file, 'println(1 + 3)\nprintln("hello")\n')?
+	os.write_file(tmp_v_file, 'println(1 + 3)\nprintln("hello")\n')!
 	assert os.is_file(tmp_v_file)
 	cmd := '$cat_cmd ${os.quoted_path(tmp_v_file)} | ${os.quoted_path(vexe)} run -'
 	res := os.execute(cmd)
diff --git a/vlib/v/tests/valgrind/valgrind_test.v b/vlib/v/tests/valgrind/valgrind_test.v
index 4b7ec0a4d9..82b393e65f 100644
--- a/vlib/v/tests/valgrind/valgrind_test.v
+++ b/vlib/v/tests/valgrind/valgrind_test.v
@@ -66,7 +66,7 @@ fn test_all() {
 	mut files := os.ls(dir) or { panic(err) }
 	files.sort()
 	//
-	wrkdir := os.join_path(os.temp_dir(), 'v', 'tests', 'valgrind')
+	wrkdir := os.join_path(os.vtmp_dir(), 'v', 'tests', 'valgrind')
 	os.mkdir_all(wrkdir) or { panic(err) }
 	os.chdir(wrkdir) or {}
 	//
diff --git a/vlib/v/util/util.v b/vlib/v/util/util.v
index 5e69155e43..0a5ea4becd 100644
--- a/vlib/v/util/util.v
+++ b/vlib/v/util/util.v
@@ -488,18 +488,10 @@ pub fn recompile_file(vexe string, file string) {
 	}
 }
 
+// get_vtmp_folder returns the path to a folder, that is writable to V programs,
+// and specific to the user. It can be overriden by setting the env variable `VTMP`.
 pub fn get_vtmp_folder() string {
-	mut vtmp := os.getenv('VTMP')
-	if vtmp.len > 0 {
-		return vtmp
-	}
-	uid := os.getuid()
-	vtmp = os.join_path_single(os.temp_dir(), 'v_$uid')
-	if !os.exists(vtmp) || !os.is_dir(vtmp) {
-		os.mkdir_all(vtmp, mode: 0o700) or { panic(err) } // keep directory private
-	}
-	os.setenv('VTMP', vtmp, true)
-	return vtmp
+	return os.vtmp_dir()
 }
 
 pub fn should_bundle_module(mod string) bool {
diff --git a/vlib/v/vcache/vcache_test.v b/vlib/v/vcache/vcache_test.v
index f7e064eab0..23e221eadb 100644
--- a/vlib/v/vcache/vcache_test.v
+++ b/vlib/v/vcache/vcache_test.v
@@ -2,7 +2,7 @@ import os
 import v.vcache
 
 const (
-	vcache_folder = os.join_path(os.temp_dir(), 'v', 'cache_folder')
+	vcache_folder = os.join_path(os.vtmp_dir(), 'v', 'cache_folder')
 )
 
 fn check_cache_entry_fpath_invariants(x string, extension string) {
diff --git a/vlib/vweb/assets/assets_test.v b/vlib/vweb/assets/assets_test.v
index b9b804c778..0de49bac27 100644
--- a/vlib/vweb/assets/assets_test.v
+++ b/vlib/vweb/assets/assets_test.v
@@ -1,7 +1,7 @@
 import vweb.assets
 import os
 
-const base_cache_dir = os.join_path(os.temp_dir(), 'v', 'assets_test_cache')
+const base_cache_dir = os.join_path(os.vtmp_dir(), 'v', 'assets_test_cache')
 
 fn testsuite_begin() {
 	os.mkdir_all(base_cache_dir) or {}