diff --git a/std/dynamic_library.zig b/std/dynamic_library.zig
index 10068e83a8..c0922003ce 100644
--- a/std/dynamic_library.zig
+++ b/std/dynamic_library.zig
@@ -1,11 +1,15 @@
 const builtin = @import("builtin");
 const Os = builtin.Os;
-const std = @import("std");
+
+const std = @import("index.zig");
 const mem = std.mem;
-const elf = std.elf;
 const cstr = std.cstr;
-const linux = std.os.linux;
-const windows = std.os.windows;
+const os = std.os;
+const assert = std.debug.assert;
+const elf = std.elf;
+const linux = os.linux;
+const windows = os.windows;
+const win_util = @import("os/windows/util.zig");
 
 pub const DynLib = switch (builtin.os) {
     Os.linux => LinuxDynLib,
@@ -169,17 +173,24 @@ pub const WindowsDynLib = struct {
     dll: windows.HMODULE,
 
     pub fn open(allocator: *mem.Allocator, path: []const u8) !WindowsDynLib {
-        const wpath = try std.unicode.utf8ToUtf16LeWithNull(allocator, path);
-        defer allocator.free(wpath);
+        const wpath = try win_util.sliceToPrefixedFileW(path);
         
         return WindowsDynLib {
             .allocator = allocator,
-            .dll = windows.LoadLibraryW(wpath[0..].ptr) orelse return error.FileNotFound
+            .dll = windows.LoadLibraryW(&wpath) orelse {
+                const err = windows.GetLastError();
+                switch (err) {
+                    windows.ERROR.FILE_NOT_FOUND => return error.FileNotFound,
+                    windows.ERROR.PATH_NOT_FOUND => return error.FileNotFound,
+                    windows.ERROR.MOD_NOT_FOUND => return error.FileNotFound,
+                    else => return os.unexpectedErrorWindows(err),
+                }
+            },
         };
     }
 
     pub fn close(self: *WindowsDynLib) void {
-        _ = windows.FreeLibrary(self.dll);
+        assert(windows.FreeLibrary(self.dll) != 0);
         self.* = undefined;
     }
 
@@ -187,3 +198,17 @@ pub const WindowsDynLib = struct {
         return @ptrToInt(windows.GetProcAddress(self.dll, name.ptr));
     }
 };
+
+test "dynamic_library" {
+    const libname = switch (builtin.os) {
+        Os.linux => "invalid_so.so",
+        Os.windows => "invalid_dll.dll",
+        else => return;,
+    };
+
+    const dynlib = DynLib.open(std.debug.global_allocator, libname) catch |err| {
+        assert(err == error.FileNotFound);
+        return;
+    };
+    @panic("Expected error from function");
+}
diff --git a/std/os/index.zig b/std/os/index.zig
index 1ce9bd7278..a53d1d2050 100644
--- a/std/os/index.zig
+++ b/std/os/index.zig
@@ -58,8 +58,6 @@ pub const windowsWrite = windows_util.windowsWrite;
 pub const windowsIsCygwinPty = windows_util.windowsIsCygwinPty;
 pub const windowsOpen = windows_util.windowsOpen;
 pub const windowsOpenW = windows_util.windowsOpenW;
-pub const windowsLoadDll = windows_util.windowsLoadDll;
-pub const windowsUnloadDll = windows_util.windowsUnloadDll;
 pub const createWindowsEnvBlock = windows_util.createWindowsEnvBlock;
 
 pub const WindowsCreateIoCompletionPortError = windows_util.WindowsCreateIoCompletionPortError;
diff --git a/std/os/windows/kernel32.zig b/std/os/windows/kernel32.zig
index 9fbd22b66a..7eec5faba9 100644
--- a/std/os/windows/kernel32.zig
+++ b/std/os/windows/kernel32.zig
@@ -4,10 +4,10 @@ pub extern "kernel32" stdcallcc fn CancelIoEx(hFile: HANDLE, lpOverlapped: LPOVE
 
 pub extern "kernel32" stdcallcc fn CloseHandle(hObject: HANDLE) BOOL;
 
-pub extern "kernel32" stdcallcc fn CreateDirectoryW(lpPathName: LPCWSTR, lpSecurityAttributes: ?*SECURITY_ATTRIBUTES) BOOL;
+pub extern "kernel32" stdcallcc fn CreateDirectoryW(lpPathName: [*]const u16, lpSecurityAttributes: ?*SECURITY_ATTRIBUTES) BOOL;
 
 pub extern "kernel32" stdcallcc fn CreateFileW(
-    lpFileName: LPCWSTR, // TODO null terminated pointer type
+    lpFileName: [*]const u16, // TODO null terminated pointer type
     dwDesiredAccess: DWORD,
     dwShareMode: DWORD,
     lpSecurityAttributes: ?LPSECURITY_ATTRIBUTES,
@@ -36,21 +36,21 @@ pub extern "kernel32" stdcallcc fn CreateProcessW(
     lpProcessInformation: *PROCESS_INFORMATION,
 ) BOOL;
 
-pub extern "kernel32" stdcallcc fn CreateSymbolicLinkW(lpSymlinkFileName: LPCWSTR, lpTargetFileName: LPCWSTR, dwFlags: DWORD) BOOLEAN;
+pub extern "kernel32" stdcallcc fn CreateSymbolicLinkW(lpSymlinkFileName: [*]const u16, lpTargetFileName: [*]const u16, dwFlags: DWORD) BOOLEAN;
 
 pub extern "kernel32" stdcallcc fn CreateIoCompletionPort(FileHandle: HANDLE, ExistingCompletionPort: ?HANDLE, CompletionKey: ULONG_PTR, NumberOfConcurrentThreads: DWORD) ?HANDLE;
 
 pub extern "kernel32" stdcallcc fn CreateThread(lpThreadAttributes: ?LPSECURITY_ATTRIBUTES, dwStackSize: SIZE_T, lpStartAddress: LPTHREAD_START_ROUTINE, lpParameter: ?LPVOID, dwCreationFlags: DWORD, lpThreadId: ?LPDWORD) ?HANDLE;
 
-pub extern "kernel32" stdcallcc fn DeleteFileW(lpFileName: LPCWSTR) BOOL;
+pub extern "kernel32" stdcallcc fn DeleteFileW(lpFileName: [*]const u16) BOOL;
 
 pub extern "kernel32" stdcallcc fn ExitProcess(exit_code: UINT) noreturn;
 
-pub extern "kernel32" stdcallcc fn FindFirstFileW(lpFileName: LPCWSTR, lpFindFileData: *WIN32_FIND_DATAW) HANDLE;
+pub extern "kernel32" stdcallcc fn FindFirstFileW(lpFileName: [*]const u16, lpFindFileData: *WIN32_FIND_DATAW) HANDLE;
 pub extern "kernel32" stdcallcc fn FindClose(hFindFile: HANDLE) BOOL;
 pub extern "kernel32" stdcallcc fn FindNextFileW(hFindFile: HANDLE, lpFindFileData: *WIN32_FIND_DATAW) BOOL;
 
-pub extern "kernel32" stdcallcc fn FreeEnvironmentStringsA(penv: LPSTR) BOOL;
+pub extern "kernel32" stdcallcc fn FreeEnvironmentStringsA(penv: [*]u8) BOOL;
 
 pub extern "kernel32" stdcallcc fn GetCommandLineA() LPSTR;
 
@@ -63,7 +63,7 @@ pub extern "kernel32" stdcallcc fn GetCurrentDirectoryW(nBufferLength: DWORD, lp
 pub extern "kernel32" stdcallcc fn GetCurrentThread() HANDLE;
 pub extern "kernel32" stdcallcc fn GetCurrentThreadId() DWORD;
 
-pub extern "kernel32" stdcallcc fn GetEnvironmentStringsA() ?LPSTR;
+pub extern "kernel32" stdcallcc fn GetEnvironmentStringsA() ?[*]u8;
 
 pub extern "kernel32" stdcallcc fn GetEnvironmentVariableA(lpName: LPCSTR, lpBuffer: LPSTR, nSize: DWORD) DWORD;
 
@@ -73,7 +73,7 @@ pub extern "kernel32" stdcallcc fn GetFileSizeEx(hFile: HANDLE, lpFileSize: *LAR
 
 pub extern "kernel32" stdcallcc fn GetFileAttributesW(lpFileName: [*]const WCHAR) DWORD;
 
-pub extern "kernel32" stdcallcc fn GetModuleFileNameW(hModule: ?HMODULE, lpFilename: LPWSTR, nSize: DWORD) DWORD;
+pub extern "kernel32" stdcallcc fn GetModuleFileNameW(hModule: ?HMODULE, lpFilename: [*]u16, nSize: DWORD) DWORD;
 
 pub extern "kernel32" stdcallcc fn GetModuleHandleW(lpModuleName: ?[*]const WCHAR) HMODULE;
 
@@ -88,7 +88,7 @@ pub extern "kernel32" stdcallcc fn GetFileInformationByHandleEx(
 
 pub extern "kernel32" stdcallcc fn GetFinalPathNameByHandleW(
     hFile: HANDLE,
-    lpszFilePath: LPWSTR,
+    lpszFilePath: [*]u16,
     cchFilePath: DWORD,
     dwFlags: DWORD,
 ) DWORD;
@@ -117,8 +117,8 @@ pub extern "kernel32" stdcallcc fn HeapFree(hHeap: HANDLE, dwFlags: DWORD, lpMem
 pub extern "kernel32" stdcallcc fn HeapValidate(hHeap: HANDLE, dwFlags: DWORD, lpMem: ?*const c_void) BOOL;
 
 pub extern "kernel32" stdcallcc fn MoveFileExW(
-    lpExistingFileName: LPCWSTR,
-    lpNewFileName: LPCWSTR,
+    lpExistingFileName: [*]const u16,
+    lpNewFileName: [*]const u16,
     dwFlags: DWORD,
 ) BOOL;
 
@@ -141,13 +141,13 @@ pub extern "kernel32" stdcallcc fn ReadDirectoryChangesW(
 
 pub extern "kernel32" stdcallcc fn ReadFile(
     in_hFile: HANDLE,
-    out_lpBuffer: LPSTR,
+    out_lpBuffer: [*]u8,
     in_nNumberOfBytesToRead: DWORD,
     out_lpNumberOfBytesRead: ?*DWORD,
     in_out_lpOverlapped: ?*OVERLAPPED,
 ) BOOL;
 
-pub extern "kernel32" stdcallcc fn RemoveDirectoryW(lpPathName: LPCWSTR) BOOL;
+pub extern "kernel32" stdcallcc fn RemoveDirectoryW(lpPathName: [*]const u16) BOOL;
 
 pub extern "kernel32" stdcallcc fn SetConsoleTextAttribute(hConsoleOutput: HANDLE, wAttributes: WORD) BOOL;
 
@@ -168,17 +168,17 @@ pub extern "kernel32" stdcallcc fn WaitForSingleObject(hHandle: HANDLE, dwMillis
 
 pub extern "kernel32" stdcallcc fn WriteFile(
     in_hFile: HANDLE,
-    in_lpBuffer: LPCSTR,
+    in_lpBuffer: [*]const u8,
     in_nNumberOfBytesToWrite: DWORD,
     out_lpNumberOfBytesWritten: ?*DWORD,
     in_out_lpOverlapped: ?*OVERLAPPED,
 ) BOOL;
 
-pub extern "kernel32" stdcallcc fn WriteFileEx(hFile: HANDLE, lpBuffer: LPCSTR, nNumberOfBytesToWrite: DWORD, lpOverlapped: LPOVERLAPPED, lpCompletionRoutine: LPOVERLAPPED_COMPLETION_ROUTINE) BOOL;
+pub extern "kernel32" stdcallcc fn WriteFileEx(hFile: HANDLE, lpBuffer: [*]const u8, nNumberOfBytesToWrite: DWORD, lpOverlapped: LPOVERLAPPED, lpCompletionRoutine: LPOVERLAPPED_COMPLETION_ROUTINE) BOOL;
 
-pub extern "kernel32" stdcallcc fn LoadLibraryW(lpLibFileName: LPCWSTR) ?HMODULE;
+pub extern "kernel32" stdcallcc fn LoadLibraryW(lpLibFileName: [*]const u16) ?HMODULE;
 
-pub extern "kernel32" stdcallcc fn GetProcAddress(hModule: HMODULE, lpProcName: LPCSTR) ?FARPROC;
+pub extern "kernel32" stdcallcc fn GetProcAddress(hModule: HMODULE, lpProcName: [*]const u8) ?FARPROC;
 
 pub extern "kernel32" stdcallcc fn FreeLibrary(hModule: HMODULE) BOOL;
 
diff --git a/std/os/windows/util.zig b/std/os/windows/util.zig
index 6534d16f5e..7d983421e0 100644
--- a/std/os/windows/util.zig
+++ b/std/os/windows/util.zig
@@ -188,37 +188,6 @@ pub fn createWindowsEnvBlock(allocator: *mem.Allocator, env_map: *const BufMap)
     return allocator.shrink(u16, result, i);
 }
 
-pub fn windowsLoadDllW(dll_path_w: [*]const u16) !windows.HMODULE {
-    return windows.LoadLibraryW(dll_path_w) orelse {
-        const err = windows.GetLastError();
-        switch (err) {
-            windows.ERROR.FILE_NOT_FOUND => return error.FileNotFound,
-            windows.ERROR.PATH_NOT_FOUND => return error.FileNotFound,
-            windows.ERROR.MOD_NOT_FOUND => return error.FileNotFound,
-            else => return os.unexpectedErrorWindows(err),
-        }
-    };
-}
-
-pub fn windowsLoadDll(dll_path: []const u8) !windows.HMODULE {
-    const dll_path_w = try sliceToPrefixedFileW(dll_path);
-    return windowsLoadDllW(&dll_path_w);
-}
-
-pub fn windowsUnloadDll(hModule: windows.HMODULE) void {
-    assert(windows.FreeLibrary(hModule) != 0);
-}
-
-test "InvalidDll" {
-    if (builtin.os != builtin.Os.windows) return error.SkipZigTest;
-
-    const handle = os.windowsLoadDll("asdf.dll") catch |err| {
-        assert(err == error.FileNotFound);
-        return;
-    };
-    @panic("Expected error from function");
-}
-
 pub fn windowsFindFirstFile(
     dir_path: []const u8,
     find_file_data: *windows.WIN32_FIND_DATAW,