diff --git a/src/evalfunc.c b/src/evalfunc.c
index ac75a7d..110935d 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -1710,7 +1710,7 @@
 	int	utf8 = 0;
 
 	if (argvars[1].v_type != VAR_UNKNOWN)
-	    utf8 = (int)tv_get_number_chk(&argvars[1], NULL);
+	    utf8 = (int)tv_get_bool_chk(&argvars[1], NULL);
 
 	if (utf8)
 	    rettv->vval.v_number = utf_ptr2char(tv_get_string(&argvars[0]));