diff --git a/ext/fiddle/lib/fiddle/types.rb b/ext/fiddle/lib/fiddle/types.rb
index 298a5e1797..3ea79368da 100644
--- a/ext/fiddle/lib/fiddle/types.rb
+++ b/ext/fiddle/lib/fiddle/types.rb
@@ -27,25 +27,26 @@ module Fiddle
   # * WORD
   module Win32Types
     def included(m) # :nodoc:
+      # https://docs.microsoft.com/en-us/windows/win32/winprog/windows-data-types
       m.module_eval{
         typealias "DWORD", "unsigned long"
-        typealias "PDWORD", "unsigned long *"
-        typealias "DWORD32", "unsigned long"
-        typealias "DWORD64", "unsigned long long"
+        typealias "PDWORD", "DWORD *"
+        typealias "DWORD32", "uint32_t"
+        typealias "DWORD64", "uint64_t"
         typealias "WORD", "unsigned short"
-        typealias "PWORD", "unsigned short *"
+        typealias "PWORD", "WORD *"
         typealias "BOOL", "int"
-        typealias "ATOM", "int"
+        typealias "ATOM", "WORD"
         typealias "BYTE", "unsigned char"
-        typealias "PBYTE", "unsigned char *"
+        typealias "PBYTE", "BYTE *"
         typealias "UINT", "unsigned int"
         typealias "ULONG", "unsigned long"
         typealias "UCHAR", "unsigned char"
-        typealias "HANDLE", "uintptr_t"
-        typealias "PHANDLE", "void*"
-        typealias "PVOID", "void*"
-        typealias "LPCSTR", "const char*"
-        typealias "LPSTR", "char*"
+        typealias "HANDLE", "PVOID"
+        typealias "PHANDLE", "HANDLE *"
+        typealias "PVOID", "void *"
+        typealias "LPCSTR", "const char *"
+        typealias "LPSTR", "char *"
         typealias "HINSTANCE", "HANDLE"
         typealias "HDC", "HANDLE"
         typealias "HWND", "HANDLE"