diff --git a/src/Package/Extension/rar.php b/src/Package/Extension/rar.php
index 70ea94174..c73c3f77f 100644
--- a/src/Package/Extension/rar.php
+++ b/src/Package/Extension/rar.php
@@ -63,24 +63,42 @@ public function patchUnrarCpuDetectionForZig(): void
     }
 
     #[BeforeStage('php', [php::class, 'makeForWindows'], 'ext-rar')]
-    #[PatchDescription('Keep the PHP Windows SDK WINVER/_WIN32_WINNT when unrar os.hpp is included')]
+    #[PatchDescription('Keep the PHP Windows SDK macros and hide PARSE_SERVER from unrar headers')]
     public function patchUnrarWindowsVersion(): void
     {
         $file = $this->getBuildDir() . '/unrar/os.hpp';
-        if (!is_file($file)) {
-            return;
+        if (is_file($file)) {
+            // unrar/os.hpp unconditionally changes WINVER/_WIN32_WINNT to Windows XP.
+            // PHP's Windows build already defines them for the modern SDK, so keep the
+            // values the build already selected (this silences the macro warnings).
+            FileSystem::replaceFileRegex(
+                $file,
+                '/^#define WINVER _WIN32_WINNT_WINXP\r?\n#define _WIN32_WINNT _WIN32_WINNT_WINXP/m',
+                "#ifndef WINVER\n#define WINVER _WIN32_WINNT_WINXP\n#endif\n"
+                . "#ifndef _WIN32_WINNT\n#define _WIN32_WINNT _WIN32_WINNT_WINXP\n#endif"
+            );
         }
 
-        // unrar/os.hpp unconditionally changes WINVER/_WIN32_WINNT to Windows XP.
-        // PHP's Windows build already defines them for the modern SDK, and the generated
-        // main/internal_functions.c includes this header before urlmon.h. Mixing SDK
-        // versions in one TU makes urlmon.h fail with C2059 around PARSEACTION, which
-        // breaks every spc-max build. Keep the values the build already selected.
-        FileSystem::replaceFileRegex(
-            $file,
-            '/^#define WINVER _WIN32_WINNT_WINXP\r?\n#define _WIN32_WINNT _WIN32_WINNT_WINXP/m',
-            "#ifndef WINVER\n#define WINVER _WIN32_WINNT_WINXP\n#endif\n"
-            . "#ifndef _WIN32_WINNT\n#define _WIN32_WINNT _WIN32_WINNT_WINXP\n#endif"
+        // php_variables.h defines PARSE_SERVER as 5. unrar's os.hpp includes
+        // shlwapi.h, which includes objbase.h -> urlmon.h, whose PARSEACTION enum
+        // also has a PARSE_SERVER member. The macro turns that member into
+        // "5 = (PARSE_MIME + 1)" and breaks main/internal_functions.c on MSVC.
+        $header = $this->getBuildDir() . '/php_rar.h';
+        if (!is_file($header)) {
+            return;
+        }
+        $content = FileSystem::readFile($header);
+        if (str_contains($content, 'SPC_RAR_PARSE_SERVER_UNDEF')) {
+            return;
+        }
+        $content = str_replace(
+            '#include "unrar/os.hpp"',
+            "/* SPC_RAR_PARSE_SERVER_UNDEF: urlmon.h (via shlwapi.h -> objbase.h) declares\n"
+            . " * PARSE_SERVER, but php_variables.h defines it as a macro. */\n"
+            . "#ifdef PARSE_SERVER\n#undef PARSE_SERVER\n#endif\n"
+            . '#include "unrar/os.hpp"',
+            $content
         );
+        FileSystem::writeFile($header, $content);
     }
 }