diff --git a/third_party/utf8rewind/utf8rewind.h b/third_party/utf8rewind/utf8rewind.h
index fce17d2f..e89c64cb 100644
--- a/third_party/utf8rewind/utf8rewind.h
+++ b/third_party/utf8rewind/utf8rewind.h
@@ -69,6 +69,12 @@
 #include <string.h>
 #include <wchar.h>
 
+#if defined(LINUX) || defined(OSX)
+  #include <strings.h>
+  #include <unistd.h>
+  #include <sys/types.h>
+#endif
+
 /*!
 	\addtogroup version
 	\{
@@ -1867,4 +1873,4 @@ UTF8_API size_t utf8iscategory(const char* input, size_t inputSize, size_t flags
 	\}
 */
 
-#endif /* _UTF8REWIND_H_ */
\ No newline at end of file
+#endif /* _UTF8REWIND_H_ */