1 files changed, 1 insertions, 0 deletions

diff --git a/src/coding.c b/src/coding.c
index a90795d781b..f2af9f5bf35 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -5217,6 +5217,7 @@ decode_coding_string (str, coding, nocopy)
     {
       /* Decoding routines expect the source text to be unibyte.  */
       str = Fstring_as_unibyte (str);
+      to_byte = STRING_BYTES (XSTRING (str));
       nocopy = 1;
       coding->src_multibyte = 0;
     }