diff --git a/src/window.c b/src/window.c
index 9530ef5..c7905ae 100644
--- a/src/window.c
+++ b/src/window.c
@@ -6746,11 +6746,11 @@
     m->match.regprog = regprog;
     m->match.rmm_ic = FALSE;
     m->match.rmm_maxcol = 0;
-#ifdef FEAT_CONCEAL
+# if defined(FEAT_CONCEAL) && defined(FEAT_MBYTE)
     m->conceal_char = 0;
     if (conceal_char != NULL)
 	m->conceal_char = (*mb_ptr2char)(conceal_char);
-#endif
+# endif
 
     /* Set up position matches */
     if (pos_list != NULL)