diff --git a/onnxruntime/core/providers/cpu/nn/string_normalizer.cc b/onnxruntime/core/providers/cpu/nn/string_normalizer.cc
index 330b92d4a8..27407e9999 100644
--- a/onnxruntime/core/providers/cpu/nn/string_normalizer.cc
+++ b/onnxruntime/core/providers/cpu/nn/string_normalizer.cc
@@ -201,7 +201,16 @@ class Utf8Converter {
 
 #endif
 
-const std::string default_locale("en_US.UTF-8");  // All non-MS
+#if defined(__APPLE__)
+#include <TargetConditionals.h>
+#if TARGET_OS_IPHONE || TARGET_OS_SIMULATOR
+const std::string default_locale("en-US.UTF-8");
+#else
+const std::string default_locale("en_US.UTF-8");  // Other kinds of Apple Platforms including MacOS, etc
+#endif
+#else
+const std::string default_locale("en_US.UTF-8");  // All non-MS and not Apple
+#endif
 
 #endif  // _MSC_VER