diff --git a/lib/std/child_process.zig b/lib/std/child_process.zig
index a76dfd3528..02d8693e2c 100644
--- a/lib/std/child_process.zig
+++ b/lib/std/child_process.zig
@@ -582,9 +582,7 @@ pub const ChildProcess = struct {
         };
         var piProcInfo: windows.PROCESS_INFORMATION = undefined;
 
-        const cwd_slice = if (self.cwd) |cwd| try cstr.addNullByte(self.allocator, cwd) else null;
-        defer if (cwd_slice) |cwd| self.allocator.free(cwd);
-        const cwd_w = if (cwd_slice) |cwd| try unicode.utf8ToUtf16LeWithNull(self.allocator, cwd) else null;
+        const cwd_w = if (self.cwd) |cwd| try unicode.utf8ToUtf16LeWithNull(self.allocator, cwd) else null;
         defer if (cwd_w) |cwd| self.allocator.free(cwd);
         const cwd_w_ptr = if (cwd_w) |cwd| cwd.ptr else null;
 
@@ -701,7 +699,7 @@ pub const ChildProcess = struct {
     }
 };
 
-fn windowsCreateProcess(app_name: [*]u16, cmd_line: [*]u16, envp_ptr: ?[*]u16, cwd_ptr: ?[*]u16, lpStartupInfo: *windows.STARTUPINFOW, lpProcessInformation: *windows.PROCESS_INFORMATION) !void {
+fn windowsCreateProcess(app_name: [*:0]u16, cmd_line: [*:0]u16, envp_ptr: ?[*]u16, cwd_ptr: ?[*:0]u16, lpStartupInfo: *windows.STARTUPINFOW, lpProcessInformation: *windows.PROCESS_INFORMATION) !void {
     // TODO the docs for environment pointer say:
     // > A pointer to the environment block for the new process. If this parameter
     // > is NULL, the new process uses the environment of the calling process.
diff --git a/lib/std/fs/file.zig b/lib/std/fs/file.zig
index 540f7d395e..c7265a8923 100644
--- a/lib/std/fs/file.zig
+++ b/lib/std/fs/file.zig
@@ -60,7 +60,7 @@ pub const File = struct {
     }
 
     /// Deprecated; call `std.fs.Dir.openFileW` directly.
-    pub fn openReadW(path_w: [*]const u16) OpenError!File {
+    pub fn openReadW(path_w: [*:0]const u16) OpenError!File {
         return std.fs.cwd().openFileW(path_w, .{});
     }
 
diff --git a/lib/std/fs/get_app_data_dir.zig b/lib/std/fs/get_app_data_dir.zig
index bbc9c4b7bb..cb26e335de 100644
--- a/lib/std/fs/get_app_data_dir.zig
+++ b/lib/std/fs/get_app_data_dir.zig
@@ -15,7 +15,7 @@ pub const GetAppDataDirError = error{
 pub fn getAppDataDir(allocator: *mem.Allocator, appname: []const u8) GetAppDataDirError![]u8 {
     switch (builtin.os) {
         .windows => {
-            var dir_path_ptr: [*]u16 = undefined;
+            var dir_path_ptr: [*:0]u16 = undefined;
             switch (os.windows.shell32.SHGetKnownFolderPath(
                 &os.windows.FOLDERID_LocalAppData,
                 os.windows.KF_FLAG_CREATE,
@@ -24,7 +24,7 @@ pub fn getAppDataDir(allocator: *mem.Allocator, appname: []const u8) GetAppDataD
             )) {
                 os.windows.S_OK => {
                     defer os.windows.ole32.CoTaskMemFree(@ptrCast(*c_void, dir_path_ptr));
-                    const global_dir = unicode.utf16leToUtf8Alloc(allocator, utf16lePtrSlice(dir_path_ptr)) catch |err| switch (err) {
+                    const global_dir = unicode.utf16leToUtf8Alloc(allocator, mem.toSliceConst(u16, dir_path_ptr)) catch |err| switch (err) {
                         error.UnexpectedSecondSurrogateHalf => return error.AppDataDirUnavailable,
                         error.ExpectedSecondSurrogateHalf => return error.AppDataDirUnavailable,
                         error.DanglingSurrogateHalf => return error.AppDataDirUnavailable,
@@ -55,12 +55,6 @@ pub fn getAppDataDir(allocator: *mem.Allocator, appname: []const u8) GetAppDataD
     }
 }
 
-fn utf16lePtrSlice(ptr: [*]const u16) []const u16 {
-    var index: usize = 0;
-    while (ptr[index] != 0) : (index += 1) {}
-    return ptr[0..index];
-}
-
 test "getAppDataDir" {
     var buf: [512]u8 = undefined;
     const allocator = &std.heap.FixedBufferAllocator.init(buf[0..]).allocator;
diff --git a/lib/std/os.zig b/lib/std/os.zig
index 676d249e87..c39891c6b0 100644
--- a/lib/std/os.zig
+++ b/lib/std/os.zig
@@ -2632,9 +2632,7 @@ pub fn realpathW(pathname: [*:0]const u16, out_buffer: *[MAX_PATH_BYTES]u8) Real
     defer windows.CloseHandle(h_file);
 
     var wide_buf: [windows.PATH_MAX_WIDE]u16 = undefined;
-    const wide_len = try windows.GetFinalPathNameByHandleW(h_file, &wide_buf, wide_buf.len, windows.VOLUME_NAME_DOS);
-    assert(wide_len <= wide_buf.len);
-    const wide_slice = wide_buf[0..wide_len];
+    const wide_slice = try windows.GetFinalPathNameByHandleW(h_file, &wide_buf, wide_buf.len, windows.VOLUME_NAME_DOS);
 
     // Windows returns \\?\ prepended to the path.
     // We strip it to make this function consistent across platforms.
diff --git a/lib/std/os/uefi/protocols/simple_text_output_protocol.zig b/lib/std/os/uefi/protocols/simple_text_output_protocol.zig
index 78358214a2..2a643ec834 100644
--- a/lib/std/os/uefi/protocols/simple_text_output_protocol.zig
+++ b/lib/std/os/uefi/protocols/simple_text_output_protocol.zig
@@ -4,8 +4,8 @@ const Guid = uefi.Guid;
 /// Character output devices
 pub const SimpleTextOutputProtocol = extern struct {
     _reset: extern fn (*const SimpleTextOutputProtocol, bool) usize,
-    _output_string: extern fn (*const SimpleTextOutputProtocol, [*]const u16) usize,
-    _test_string: extern fn (*const SimpleTextOutputProtocol, [*]const u16) usize,
+    _output_string: extern fn (*const SimpleTextOutputProtocol, [*:0]const u16) usize,
+    _test_string: extern fn (*const SimpleTextOutputProtocol, [*:0]const u16) usize,
     _query_mode: extern fn (*const SimpleTextOutputProtocol, usize, *usize, *usize) usize,
     _set_mode: extern fn (*const SimpleTextOutputProtocol, usize) usize,
     _set_attribute: extern fn (*const SimpleTextOutputProtocol, usize) usize,
@@ -20,12 +20,12 @@ pub const SimpleTextOutputProtocol = extern struct {
     }
 
     /// Writes a string to the output device.
-    pub fn outputString(self: *const SimpleTextOutputProtocol, msg: [*]const u16) usize {
+    pub fn outputString(self: *const SimpleTextOutputProtocol, msg: [*:0]const u16) usize {
         return self._output_string(self, msg);
     }
 
     /// Verifies that all characters in a string can be output to the target device.
-    pub fn testString(self: *const SimpleTextOutputProtocol, msg: [*]const u16) usize {
+    pub fn testString(self: *const SimpleTextOutputProtocol, msg: [*:0]const u16) usize {
         return self._test_string(self, msg);
     }
 
diff --git a/lib/std/os/uefi/tables/runtime_services.zig b/lib/std/os/uefi/tables/runtime_services.zig
index 39d1aa2e3e..9e6861377b 100644
--- a/lib/std/os/uefi/tables/runtime_services.zig
+++ b/lib/std/os/uefi/tables/runtime_services.zig
@@ -25,13 +25,13 @@ pub const RuntimeServices = extern struct {
     convertPointer: usize, // TODO
 
     /// Returns the value of a variable.
-    getVariable: extern fn ([*]const u16, *align(8) const Guid, ?*u32, *usize, ?*c_void) usize,
+    getVariable: extern fn ([*:0]const u16, *align(8) const Guid, ?*u32, *usize, ?*c_void) usize,
 
     /// Enumerates the current variable names.
     getNextVariableName: extern fn (*usize, [*]u16, *align(8) Guid) usize,
 
     /// Sets the value of a variable.
-    setVariable: extern fn ([*]const u16, *align(8) const Guid, u32, usize, *c_void) usize,
+    setVariable: extern fn ([*:0]const u16, *align(8) const Guid, u32, usize, *c_void) usize,
 
     getNextHighMonotonicCount: usize, // TODO
 
diff --git a/lib/std/os/uefi/tables/system_table.zig b/lib/std/os/uefi/tables/system_table.zig
index 6d949ee19c..40fec34d44 100644
--- a/lib/std/os/uefi/tables/system_table.zig
+++ b/lib/std/os/uefi/tables/system_table.zig
@@ -19,7 +19,7 @@ pub const SystemTable = extern struct {
     hdr: TableHeader,
 
     /// A null-terminated string that identifies the vendor that produces the system firmware of the platform.
-    firmware_vendor: [*]u16,
+    firmware_vendor: [*:0]u16,
     firmware_revision: u32,
     console_in_handle: ?Handle,
     con_in: ?*SimpleTextInputProtocol,
diff --git a/lib/std/os/windows.zig b/lib/std/os/windows.zig
index b7b1edeb89..a6aeaa439a 100644
--- a/lib/std/os/windows.zig
+++ b/lib/std/os/windows.zig
@@ -60,7 +60,7 @@ pub fn CreateFile(
 }
 
 pub fn CreateFileW(
-    file_path_w: [*]const u16,
+    file_path_w: [*:0]const u16,
     desired_access: DWORD,
     share_mode: DWORD,
     lpSecurityAttributes: ?LPSECURITY_ATTRIBUTES,
@@ -425,8 +425,8 @@ pub fn CreateSymbolicLink(
 }
 
 pub fn CreateSymbolicLinkW(
-    sym_link_path: [*]const u16,
-    target_path: [*]const u16,
+    sym_link_path: [*:0]const u16,
+    target_path: [*:0]const u16,
     flags: DWORD,
 ) CreateSymbolicLinkError!void {
     if (kernel32.CreateSymbolicLinkW(sym_link_path, target_path, flags) == 0) {
@@ -449,7 +449,7 @@ pub fn DeleteFile(filename: []const u8) DeleteFileError!void {
     return DeleteFileW(&filename_w);
 }
 
-pub fn DeleteFileW(filename: [*]const u16) DeleteFileError!void {
+pub fn DeleteFileW(filename: [*:0]const u16) DeleteFileError!void {
     if (kernel32.DeleteFileW(filename) == 0) {
         switch (kernel32.GetLastError()) {
             ERROR.FILE_NOT_FOUND => return error.FileNotFound,
@@ -471,7 +471,7 @@ pub fn MoveFileEx(old_path: []const u8, new_path: []const u8, flags: DWORD) Move
     return MoveFileExW(&old_path_w, &new_path_w, flags);
 }
 
-pub fn MoveFileExW(old_path: [*]const u16, new_path: [*]const u16, flags: DWORD) MoveFileError!void {
+pub fn MoveFileExW(old_path: [*:0]const u16, new_path: [*:0]const u16, flags: DWORD) MoveFileError!void {
     if (kernel32.MoveFileExW(old_path, new_path, flags) == 0) {
         switch (kernel32.GetLastError()) {
             else => |err| return unexpectedError(err),
@@ -490,7 +490,7 @@ pub fn CreateDirectory(pathname: []const u8, attrs: ?*SECURITY_ATTRIBUTES) Creat
     return CreateDirectoryW(&pathname_w, attrs);
 }
 
-pub fn CreateDirectoryW(pathname: [*]const u16, attrs: ?*SECURITY_ATTRIBUTES) CreateDirectoryError!void {
+pub fn CreateDirectoryW(pathname: [*:0]const u16, attrs: ?*SECURITY_ATTRIBUTES) CreateDirectoryError!void {
     if (kernel32.CreateDirectoryW(pathname, attrs) == 0) {
         switch (kernel32.GetLastError()) {
             ERROR.ALREADY_EXISTS => return error.PathAlreadyExists,
@@ -511,7 +511,7 @@ pub fn RemoveDirectory(dir_path: []const u8) RemoveDirectoryError!void {
     return RemoveDirectoryW(&dir_path_w);
 }
 
-pub fn RemoveDirectoryW(dir_path_w: [*]const u16) RemoveDirectoryError!void {
+pub fn RemoveDirectoryW(dir_path_w: [*:0]const u16) RemoveDirectoryError!void {
     if (kernel32.RemoveDirectoryW(dir_path_w) == 0) {
         switch (kernel32.GetLastError()) {
             ERROR.PATH_NOT_FOUND => return error.FileNotFound,
@@ -602,7 +602,7 @@ pub fn GetFinalPathNameByHandleW(
     buf_ptr: [*]u16,
     buf_len: DWORD,
     flags: DWORD,
-) GetFinalPathNameByHandleError!DWORD {
+) GetFinalPathNameByHandleError![:0]u16 {
     const rc = kernel32.GetFinalPathNameByHandleW(hFile, buf_ptr, buf_len, flags);
     if (rc == 0) {
         switch (kernel32.GetLastError()) {
@@ -614,7 +614,7 @@ pub fn GetFinalPathNameByHandleW(
             else => |err| return unexpectedError(err),
         }
     }
-    return rc;
+    return buf_ptr[0..rc :0];
 }
 
 pub const GetFileSizeError = error{Unexpected};
@@ -640,7 +640,7 @@ pub fn GetFileAttributes(filename: []const u8) GetFileAttributesError!DWORD {
     return GetFileAttributesW(&filename_w);
 }
 
-pub fn GetFileAttributesW(lpFileName: [*]const u16) GetFileAttributesError!DWORD {
+pub fn GetFileAttributesW(lpFileName: [*:0]const u16) GetFileAttributesError!DWORD {
     const rc = kernel32.GetFileAttributesW(lpFileName);
     if (rc == INVALID_FILE_ATTRIBUTES) {
         switch (kernel32.GetLastError()) {
@@ -733,14 +733,14 @@ pub fn WSAIoctl(
 
 const GetModuleFileNameError = error{Unexpected};
 
-pub fn GetModuleFileNameW(hModule: ?HMODULE, buf_ptr: [*]u16, buf_len: DWORD) GetModuleFileNameError![]u16 {
+pub fn GetModuleFileNameW(hModule: ?HMODULE, buf_ptr: [*]u16, buf_len: DWORD) GetModuleFileNameError![:0]u16 {
     const rc = kernel32.GetModuleFileNameW(hModule, buf_ptr, buf_len);
     if (rc == 0) {
         switch (kernel32.GetLastError()) {
             else => |err| return unexpectedError(err),
         }
     }
-    return buf_ptr[0..rc];
+    return buf_ptr[0..rc :0];
 }
 
 pub const TerminateProcessError = error{Unexpected};
@@ -779,11 +779,11 @@ pub fn SetConsoleTextAttribute(hConsoleOutput: HANDLE, wAttributes: WORD) SetCon
 
 pub const GetEnvironmentStringsError = error{OutOfMemory};
 
-pub fn GetEnvironmentStringsW() GetEnvironmentStringsError![*]u16 {
+pub fn GetEnvironmentStringsW() GetEnvironmentStringsError![*:0]u16 {
     return kernel32.GetEnvironmentStringsW() orelse return error.OutOfMemory;
 }
 
-pub fn FreeEnvironmentStringsW(penv: [*]u16) void {
+pub fn FreeEnvironmentStringsW(penv: [*:0]u16) void {
     assert(kernel32.FreeEnvironmentStringsW(penv) != 0);
 }
 
@@ -792,7 +792,7 @@ pub const GetEnvironmentVariableError = error{
     Unexpected,
 };
 
-pub fn GetEnvironmentVariableW(lpName: LPWSTR, lpBuffer: LPWSTR, nSize: DWORD) GetEnvironmentVariableError!DWORD {
+pub fn GetEnvironmentVariableW(lpName: LPWSTR, lpBuffer: [*]u16, nSize: DWORD) GetEnvironmentVariableError!DWORD {
     const rc = kernel32.GetEnvironmentVariableW(lpName, lpBuffer, nSize);
     if (rc == 0) {
         switch (kernel32.GetLastError()) {
@@ -850,7 +850,7 @@ pub const LoadLibraryError = error{
     Unexpected,
 };
 
-pub fn LoadLibraryW(lpLibFileName: [*]const u16) LoadLibraryError!HMODULE {
+pub fn LoadLibraryW(lpLibFileName: [*:0]const u16) LoadLibraryError!HMODULE {
     return kernel32.LoadLibraryW(lpLibFileName) orelse {
         switch (kernel32.GetLastError()) {
             ERROR.FILE_NOT_FOUND => return error.FileNotFound,
diff --git a/lib/std/os/windows/bits.zig b/lib/std/os/windows/bits.zig
index 7d87ae075a..328732e0c7 100644
--- a/lib/std/os/windows/bits.zig
+++ b/lib/std/os/windows/bits.zig
@@ -33,17 +33,17 @@ pub const FARPROC = *@OpaqueType();
 pub const INT = c_int;
 pub const LPBYTE = *BYTE;
 pub const LPCH = *CHAR;
-pub const LPCSTR = [*]const CHAR;
-pub const LPCTSTR = [*]const TCHAR;
+pub const LPCSTR = [*:0]const CHAR;
+pub const LPCTSTR = [*:0]const TCHAR;
 pub const LPCVOID = *const c_void;
 pub const LPDWORD = *DWORD;
-pub const LPSTR = [*]CHAR;
+pub const LPSTR = [*:0]CHAR;
 pub const LPTSTR = if (UNICODE) LPWSTR else LPSTR;
 pub const LPVOID = *c_void;
-pub const LPWSTR = [*]WCHAR;
-pub const LPCWSTR = [*]const WCHAR;
+pub const LPWSTR = [*:0]WCHAR;
+pub const LPCWSTR = [*:0]const WCHAR;
 pub const PVOID = *c_void;
-pub const PWSTR = [*]WCHAR;
+pub const PWSTR = [*:0]WCHAR;
 pub const SIZE_T = usize;
 pub const TCHAR = if (UNICODE) WCHAR else u8;
 pub const UINT = c_uint;
diff --git a/lib/std/os/windows/kernel32.zig b/lib/std/os/windows/kernel32.zig
index 1af68f4abd..9ec40240b6 100644
--- a/lib/std/os/windows/kernel32.zig
+++ b/lib/std/os/windows/kernel32.zig
@@ -7,7 +7,7 @@ pub extern "kernel32" fn CancelIoEx(hFile: HANDLE, lpOverlapped: LPOVERLAPPED) c
 
 pub extern "kernel32" fn CloseHandle(hObject: HANDLE) callconv(.Stdcall) BOOL;
 
-pub extern "kernel32" fn CreateDirectoryW(lpPathName: [*]const u16, lpSecurityAttributes: ?*SECURITY_ATTRIBUTES) callconv(.Stdcall) BOOL;
+pub extern "kernel32" fn CreateDirectoryW(lpPathName: [*:0]const u16, lpSecurityAttributes: ?*SECURITY_ATTRIBUTES) callconv(.Stdcall) BOOL;
 
 pub extern "kernel32" fn CreateEventExW(
     lpEventAttributes: ?*SECURITY_ATTRIBUTES,
@@ -17,7 +17,7 @@ pub extern "kernel32" fn CreateEventExW(
 ) callconv(.Stdcall) ?HANDLE;
 
 pub extern "kernel32" fn CreateFileW(
-    lpFileName: [*]const u16, // TODO null terminated pointer type
+    lpFileName: [*:0]const u16,
     dwDesiredAccess: DWORD,
     dwShareMode: DWORD,
     lpSecurityAttributes: ?LPSECURITY_ATTRIBUTES,
@@ -46,7 +46,7 @@ pub extern "kernel32" fn CreateProcessW(
     lpProcessInformation: *PROCESS_INFORMATION,
 ) callconv(.Stdcall) BOOL;
 
-pub extern "kernel32" fn CreateSymbolicLinkW(lpSymlinkFileName: [*]const u16, lpTargetFileName: [*]const u16, dwFlags: DWORD) callconv(.Stdcall) BOOLEAN;
+pub extern "kernel32" fn CreateSymbolicLinkW(lpSymlinkFileName: [*:0]const u16, lpTargetFileName: [*:0]const u16, dwFlags: DWORD) callconv(.Stdcall) BOOLEAN;
 
 pub extern "kernel32" fn CreateIoCompletionPort(FileHandle: HANDLE, ExistingCompletionPort: ?HANDLE, CompletionKey: ULONG_PTR, NumberOfConcurrentThreads: DWORD) callconv(.Stdcall) ?HANDLE;
 
@@ -63,19 +63,19 @@ pub extern "kernel32" fn DeviceIoControl(
     lpOverlapped: ?*OVERLAPPED,
 ) callconv(.Stdcall) BOOL;
 
-pub extern "kernel32" fn DeleteFileW(lpFileName: [*]const u16) callconv(.Stdcall) BOOL;
+pub extern "kernel32" fn DeleteFileW(lpFileName: [*:0]const u16) callconv(.Stdcall) BOOL;
 
 pub extern "kernel32" fn DuplicateHandle(hSourceProcessHandle: HANDLE, hSourceHandle: HANDLE, hTargetProcessHandle: HANDLE, lpTargetHandle: *HANDLE, dwDesiredAccess: DWORD, bInheritHandle: BOOL, dwOptions: DWORD) callconv(.Stdcall) BOOL;
 
 pub extern "kernel32" fn ExitProcess(exit_code: UINT) callconv(.Stdcall) noreturn;
 
-pub extern "kernel32" fn FindFirstFileW(lpFileName: [*]const u16, lpFindFileData: *WIN32_FIND_DATAW) callconv(.Stdcall) HANDLE;
+pub extern "kernel32" fn FindFirstFileW(lpFileName: [*:0]const u16, lpFindFileData: *WIN32_FIND_DATAW) callconv(.Stdcall) HANDLE;
 pub extern "kernel32" fn FindClose(hFindFile: HANDLE) callconv(.Stdcall) BOOL;
 pub extern "kernel32" fn FindNextFileW(hFindFile: HANDLE, lpFindFileData: *WIN32_FIND_DATAW) callconv(.Stdcall) BOOL;
 
-pub extern "kernel32" fn FormatMessageW(dwFlags: DWORD, lpSource: ?LPVOID, dwMessageId: DWORD, dwLanguageId: DWORD, lpBuffer: LPWSTR, nSize: DWORD, Arguments: ?*va_list) callconv(.Stdcall) DWORD;
+pub extern "kernel32" fn FormatMessageW(dwFlags: DWORD, lpSource: ?LPVOID, dwMessageId: DWORD, dwLanguageId: DWORD, lpBuffer: [*]u16, nSize: DWORD, Arguments: ?*va_list) callconv(.Stdcall) DWORD;
 
-pub extern "kernel32" fn FreeEnvironmentStringsW(penv: [*]u16) callconv(.Stdcall) BOOL;
+pub extern "kernel32" fn FreeEnvironmentStringsW(penv: [*:0]u16) callconv(.Stdcall) BOOL;
 
 pub extern "kernel32" fn GetCommandLineA() callconv(.Stdcall) LPSTR;
 
@@ -88,9 +88,9 @@ pub extern "kernel32" fn GetCurrentDirectoryW(nBufferLength: DWORD, lpBuffer: ?[
 pub extern "kernel32" fn GetCurrentThread() callconv(.Stdcall) HANDLE;
 pub extern "kernel32" fn GetCurrentThreadId() callconv(.Stdcall) DWORD;
 
-pub extern "kernel32" fn GetEnvironmentStringsW() callconv(.Stdcall) ?[*]u16;
+pub extern "kernel32" fn GetEnvironmentStringsW() callconv(.Stdcall) ?[*:0]u16;
 
-pub extern "kernel32" fn GetEnvironmentVariableW(lpName: LPWSTR, lpBuffer: LPWSTR, nSize: DWORD) callconv(.Stdcall) DWORD;
+pub extern "kernel32" fn GetEnvironmentVariableW(lpName: LPWSTR, lpBuffer: [*]u16, nSize: DWORD) callconv(.Stdcall) DWORD;
 
 pub extern "kernel32" fn GetExitCodeProcess(hProcess: HANDLE, lpExitCode: *DWORD) callconv(.Stdcall) BOOL;
 
@@ -150,8 +150,8 @@ pub extern "kernel32" fn VirtualAlloc(lpAddress: ?LPVOID, dwSize: SIZE_T, flAllo
 pub extern "kernel32" fn VirtualFree(lpAddress: ?LPVOID, dwSize: SIZE_T, dwFreeType: DWORD) callconv(.Stdcall) BOOL;
 
 pub extern "kernel32" fn MoveFileExW(
-    lpExistingFileName: [*]const u16,
-    lpNewFileName: [*]const u16,
+    lpExistingFileName: [*:0]const u16,
+    lpNewFileName: [*:0]const u16,
     dwFlags: DWORD,
 ) callconv(.Stdcall) BOOL;
 
@@ -180,7 +180,7 @@ pub extern "kernel32" fn ReadFile(
     in_out_lpOverlapped: ?*OVERLAPPED,
 ) callconv(.Stdcall) BOOL;
 
-pub extern "kernel32" fn RemoveDirectoryW(lpPathName: [*]const u16) callconv(.Stdcall) BOOL;
+pub extern "kernel32" fn RemoveDirectoryW(lpPathName: [*:0]const u16) callconv(.Stdcall) BOOL;
 
 pub extern "kernel32" fn SetConsoleTextAttribute(hConsoleOutput: HANDLE, wAttributes: WORD) callconv(.Stdcall) BOOL;
 
@@ -234,7 +234,7 @@ pub extern "kernel32" fn WriteFile(
 
 pub extern "kernel32" fn WriteFileEx(hFile: HANDLE, lpBuffer: [*]const u8, nNumberOfBytesToWrite: DWORD, lpOverlapped: LPOVERLAPPED, lpCompletionRoutine: LPOVERLAPPED_COMPLETION_ROUTINE) callconv(.Stdcall) BOOL;
 
-pub extern "kernel32" fn LoadLibraryW(lpLibFileName: [*]const u16) callconv(.Stdcall) ?HMODULE;
+pub extern "kernel32" fn LoadLibraryW(lpLibFileName: [*:0]const u16) callconv(.Stdcall) ?HMODULE;
 
 pub extern "kernel32" fn GetProcAddress(hModule: HMODULE, lpProcName: [*]const u8) callconv(.Stdcall) ?FARPROC;
 
diff --git a/lib/std/os/windows/ntdll.zig b/lib/std/os/windows/ntdll.zig
index 695cd77274..08f22386f9 100644
--- a/lib/std/os/windows/ntdll.zig
+++ b/lib/std/os/windows/ntdll.zig
@@ -35,9 +35,9 @@ pub extern "NtDll" fn NtDeviceIoControlFile(
 ) callconv(.Stdcall) NTSTATUS;
 pub extern "NtDll" fn NtClose(Handle: HANDLE) callconv(.Stdcall) NTSTATUS;
 pub extern "NtDll" fn RtlDosPathNameToNtPathName_U(
-    DosPathName: [*]const u16,
+    DosPathName: [*:0]const u16,
     NtPathName: *UNICODE_STRING,
-    NtFileNamePart: ?*?[*]const u16,
+    NtFileNamePart: ?*?[*:0]const u16,
     DirectoryInfo: ?*CURDIR,
 ) callconv(.Stdcall) BOOL;
 pub extern "NtDll" fn RtlFreeUnicodeString(UnicodeString: *UNICODE_STRING) callconv(.Stdcall) void;
diff --git a/lib/std/os/windows/shell32.zig b/lib/std/os/windows/shell32.zig
index aa1667d01d..762589c6de 100644
--- a/lib/std/os/windows/shell32.zig
+++ b/lib/std/os/windows/shell32.zig
@@ -1,3 +1,3 @@
 usingnamespace @import("bits.zig");
 
-pub extern "shell32" fn SHGetKnownFolderPath(rfid: *const KNOWNFOLDERID, dwFlags: DWORD, hToken: ?HANDLE, ppszPath: *[*]WCHAR) callconv(.Stdcall) HRESULT;
+pub extern "shell32" fn SHGetKnownFolderPath(rfid: *const KNOWNFOLDERID, dwFlags: DWORD, hToken: ?HANDLE, ppszPath: *[*:0]WCHAR) callconv(.Stdcall) HRESULT;
diff --git a/lib/std/unicode.zig b/lib/std/unicode.zig
index 4dfe1c87d3..3d16748447 100644
--- a/lib/std/unicode.zig
+++ b/lib/std/unicode.zig
@@ -544,8 +544,7 @@ test "utf16leToUtf8" {
     }
 }
 
-/// TODO type for null terminated pointer
-pub fn utf8ToUtf16LeWithNull(allocator: *mem.Allocator, utf8: []const u8) ![]u16 {
+pub fn utf8ToUtf16LeWithNull(allocator: *mem.Allocator, utf8: []const u8) ![:0]u16 {
     var result = std.ArrayList(u16).init(allocator);
     // optimistically guess that it will not require surrogate pairs
     try result.ensureCapacity(utf8.len + 1);
@@ -567,7 +566,7 @@ pub fn utf8ToUtf16LeWithNull(allocator: *mem.Allocator, utf8: []const u8) ![]u16
     }
 
     try result.append(0);
-    return result.toOwnedSlice();
+    return result.toOwnedSlice()[0..:0];
 }
 
 /// Returns index of next character. If exact fit, returned index equals output slice length.