diff --git a/intl/lwbrk/src/th_char.h b/intl/lwbrk/src/th_char.h
index cb710fc21573..05a969b83ced 100644
--- a/intl/lwbrk/src/th_char.h
+++ b/intl/lwbrk/src/th_char.h
@@ -16,7 +16,15 @@ purpose.  It is provided "as is" without express or implied warranty.
 typedef unsigned char	tis_char;
 
 #ifdef TH_UNICODE
+/*
+ * The char16_t type is only usable in C++ code, so we need this ugly hack to
+ * select a binary compatible C type for the expat C code to use.
+ */
+#ifdef __cplusplus
 typedef char16_t	th_char;
+#else
+typedef uint16_t	th_char;
+#endif
 #define TH_THAIBEGIN_	0x0e00
 #define th_isthai(c)	(0x0e00 <= (c) && (c) <= 0x0e5f)
 #else