diff --git a/jerry-core/lit/lit-strings.cpp b/jerry-core/lit/lit-strings.cpp
index 0392181456..9a53be2bf4 100644
--- a/jerry-core/lit/lit-strings.cpp
+++ b/jerry-core/lit/lit-strings.cpp
@@ -762,7 +762,7 @@ lit_utf8_string_code_unit_at (const lit_utf8_byte_t *utf8_buf_p, /**< utf-8 stri
  *
  * @return number of bytes occupied in CESU-8
  */
-lit_utf8_size_t
+lit_utf8_size_t __attr_always_inline___
 lit_get_unicode_char_size_by_utf8_first_byte (const lit_utf8_byte_t first_byte) /**< buffer with characters */
 {
   if ((first_byte & LIT_UTF8_1_BYTE_MASK) == LIT_UTF8_1_BYTE_MARKER)