diff --git a/rtl/win/wininc/struct.inc b/rtl/win/wininc/struct.inc
index 045a9b0cfc..0c5c0cb363 100644
--- a/rtl/win/wininc/struct.inc
+++ b/rtl/win/wininc/struct.inc
@@ -7363,7 +7363,7 @@ Const
           idCommand : longint;
           fsState : BYTE;
           fsStyle : BYTE;
-{$ifdef _WIN64}
+{$ifdef WIN64}
           bReserved : array[0..5] of BYTE;
 {$else}
           bReserved : array[0..1] of BYTE;
@@ -8592,7 +8592,7 @@ const
   IMAGE_ROM_OPTIONAL_HDR_MAGIC  = $107;
 
 type
-{$ifdef _WIN64}
+{$ifdef WIN64}
   IMAGE_OPTIONAL_HEADER = IMAGE_OPTIONAL_HEADER64;
   PIMAGE_OPTIONAL_HEADER = PIMAGE_OPTIONAL_HEADER64;
 {$else}
@@ -8636,7 +8636,7 @@ type
   TImageRomHeaders = IMAGE_ROM_HEADERS;
   PImageRomHeaders = PIMAGE_ROM_HEADERS;
 
-{$ifdef _WIN64}
+{$ifdef WIN64}
   IMAGE_NT_HEADERS = IMAGE_NT_HEADERS64;
   PIMAGE_NT_HEADERS = PIMAGE_NT_HEADERS64;
 {$else}
@@ -8804,7 +8804,7 @@ type
        end;
      PIMAGE_LOAD_CONFIG_DIRECTORY64 = ^IMAGE_LOAD_CONFIG_DIRECTORY64;
      TIMAGE_LOAD_CONFIG_DIRECTORY64 = IMAGE_LOAD_CONFIG_DIRECTORY64;
-{$ifdef _WIN64}
+{$ifdef WIN64}
      IMAGE_LOAD_CONFIG_DIRECTORY = IMAGE_LOAD_CONFIG_DIRECTORY64;
      TIMAGE_LOAD_CONFIG_DIRECTORY = TIMAGE_LOAD_CONFIG_DIRECTORY64;
      PIMAGE_LOAD_CONFIG_DIRECTORY = PIMAGE_LOAD_CONFIG_DIRECTORY64;