1 files changed, 4 insertions, 12 deletions

diff --git a/src/fns.c b/src/fns.c
index eb2c2cbcbc0..64c6778aea4 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -473,7 +473,7 @@ concat (nargs, args, target_type, last_special)
               }
           else if (STRINGP (this))
             {
-              result_len_byte += XSTRING (this)->size_byte;
+              if (STRING_MULTIBYTE (this))
                 {
                   some_multibyte = 1;
                   result_len_byte += XSTRING (this)->size_byte;
@@ -572,17 +572,9 @@ concat (nargs, args, target_type, last_special)
                       {
                         unsigned char c;
                         XSETFASTINT (elt, XSTRING (this)->data[thisindex++]);
-                        if (some_multibyte && XINT (elt) >= 0200
-                            && XINT (elt) < 0400)
-                          {
-                            c = XINT (elt);
-                            if (nonascii_insert_offset > 0)
-                              c += nonascii_insert_offset;
-                            else
-                              c += DEFAULT_NONASCII_INSERT_OFFSET;
-
-                            XSETINT (elt, c);
-                          }
+                        if (some_multibyte)
+                          XSETINT (elt,
+                                   unibyte_char_to_multibyte (XINT (elt)));
                       }
                   }
                 else if (BOOL_VECTOR_P (this))