(Fmapconcat): Use empty_unibyte_string.

diff --git a/src/fns.c b/src/fns.c
index 661a3ea1887f6aa08cfde7e8c96c9473a2d778e2..379b1321e089067bc2132ee1b76e08c27eb0d572 100644 (file)
--- a/src/fns.c
+++ b/src/fns.c
@@ -3134,7 +3134,7 @@ SEQUENCE may be a list, a vector, a bool-vector, or a string.  */)
   len = Flength (sequence);
   leni = XINT (len);
   nargs = leni + leni - 1;
-  if (nargs < 0) return build_string ("");
+  if (nargs < 0) return empty_unibyte_string;
 
   SAFE_ALLOCA_LISP (args, nargs);