diff --git a/tmux.h b/tmux.h
index aad11ffe..77285a8d 100644
--- a/tmux.h
+++ b/tmux.h
@@ -515,10 +515,11 @@ struct msg_stderr_data {
 #define ALL_MOUSE_MODES (MODE_MOUSE_STANDARD|MODE_MOUSE_BUTTON|MODE_MOUSE_ALL)
 
 /*
- * A single UTF-8 character. UTF8_SIZE must be big enough to hold at least one
- * combining character as well.
+ * A single UTF-8 character. UTF8_SIZE must be big enough to hold
+ * combining characters as well, currently at most five (of three
+ * bytes) are supported.
 */
-#define UTF8_SIZE 9
+#define UTF8_SIZE 18
 struct utf8_data {
 	u_char	data[UTF8_SIZE];
 
diff --git a/window-copy.c b/window-copy.c
index d865287a..c2d9b9ad 100644
--- a/window-copy.c
+++ b/window-copy.c
@@ -201,22 +201,10 @@ window_copy_init(struct window_pane *wp, __unused struct cmd_find_state *fs,
 	struct window_copy_mode_data	*data;
 	struct screen			*s;
 
-	wp->modedata = data = xmalloc(sizeof *data);
-
-	data->oy = 0;
-	data->cx = 0;
-	data->cy = 0;
+	wp->modedata = data = xcalloc(1, sizeof *data);
 
 	data->cursordrag = CURSORDRAG_NONE;
-
-	data->lastcx = 0;
-	data->lastsx = 0;
-
-	data->backing_written = 0;
-
 	data->lineflag = LINE_SEL_NONE;
-	data->rectflag = 0;
-	data->scroll_exit = 0;
 
 	if (wp->searchstr != NULL) {
 		data->searchtype = WINDOW_COPY_SEARCHUP;