diff --git a/Source/JavaScriptCore/API/JSStringRef.h b/Source/JavaScriptCore/API/JSStringRef.h
index bc03ed7..3e51af8 100644
--- a/Source/JavaScriptCore/API/JSStringRef.h
+++ b/Source/JavaScriptCore/API/JSStringRef.h
@@ -32,6 +32,7 @@
 #include <stdbool.h>
 #endif
 #include <stddef.h> /* for size_t */
+#include <uchar.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -46,7 +47,7 @@ extern "C" {
  character. As with all scalar types, endianness depends on the underlying
  architecture.
 */
-    typedef unsigned short JSChar;
+    typedef char16_t JSChar;
 #else
     typedef wchar_t JSChar;
 #endif
diff --git a/Source/WebKit2/Shared/API/c/WKString.h b/Source/WebKit2/Shared/API/c/WKString.h
index 4c6a204..a8f5647 100644
--- a/Source/WebKit2/Shared/API/c/WKString.h
+++ b/Source/WebKit2/Shared/API/c/WKString.h
@@ -28,6 +28,7 @@
 
 #include <WebKit/WKBase.h>
 #include <stddef.h>
+#include <uchar.h>
 
 #ifndef __cplusplus
 #include <stdbool.h>
@@ -39,7 +40,7 @@ extern "C" {
 
 #if !defined(WIN32) && !defined(_WIN32) \
     && !((defined(__CC_ARM) || defined(__ARMCC__)) && !defined(__linux__)) /* RVCT */
-    typedef unsigned short WKChar;
+    typedef char16_t WKChar;
 #else
     typedef wchar_t WKChar;
 #endif