diff --git a/include/utils/String8.h b/include/utils/String8.h
index ecc5774..c4b18a4 100644
--- a/include/utils/String8.h
+++ b/include/utils/String8.h
@@ -60,6 +60,11 @@
 /*
  * Returns the UTF-8 length of "src".
  */
+size_t utf8_length_from_utf16(const char16_t *src, size_t src_len);
+
+/*
+ * Returns the UTF-8 length of "src".
+ */
 size_t utf8_length_from_utf32(const char32_t *src, size_t src_len);
 
 /*
@@ -120,6 +125,9 @@
 size_t utf32_to_utf8(const char32_t* src, size_t src_len,
                      char* dst, size_t dst_len);
 
+size_t utf16_to_utf8(const char16_t* src, size_t src_len,
+                     char* dst, size_t dst_len);
+
 }
 
 // ---------------------------------------------------------------------------