diff --git a/src/Package/Extension/intl.php b/src/Package/Extension/intl.php
index f5e17c1f..dd7d3ffd 100644
--- a/src/Package/Extension/intl.php
+++ b/src/Package/Extension/intl.php
@@ -16,7 +16,7 @@ use StaticPHP\Util\FileSystem;
 class intl extends PhpExtensionPackage
 {
     #[BeforeStage('php', [php::class, 'buildconfForWindows'], 'ext-intl')]
-    #[PatchDescription('Fix intl config.w32: replace hardcoded true with PHP_INTL_SHARED for static build support')]
+    #[PatchDescription('Fix intl config.w32: replace hardcoded true with PHP_INTL_SHARED for static build support; add /std:c++17 required by ICU 73+')]
     public function patchBeforeBuildconfForWindows(PackageInstaller $installer): void
     {
         $php_src = $installer->getTargetPackage('php')->getSourceDir();
@@ -25,5 +25,11 @@ class intl extends PhpExtensionPackage
             'EXTENSION("intl", "php_intl.c intl_convert.c intl_convertcpp.cpp intl_error.c ", true,',
             'EXTENSION("intl", "php_intl.c intl_convert.c intl_convertcpp.cpp intl_error.c ", PHP_INTL_SHARED,'
         );
+        // ICU 73+ headers (char16ptr.h etc.) unconditionally include <string_view> which requires C++17.
+        FileSystem::replaceFileStr(
+            "{$php_src}/ext/intl/config.w32",
+            'ADD_FLAG("CFLAGS_INTL", "/EHsc',
+            'ADD_FLAG("CFLAGS_INTL", "/std:c++17 /EHsc'
+        );
     }
 }