--- a/dstr.c	2009-08-05 05:09:21.000000000 +0200
+++ b/dstr.c	2018-09-27 15:43:52.815761856 +0200
@@ -79,7 +79,7 @@
 #ifdef SAFECALL
   if(length == 0) return(ERROR);
 #endif
-  if (length > tgt->c) {
+  if (length + 1 > tgt->c) {
     if(tgt->s != NULL) free( (void *) tgt->s);
     tgt->s = (wchar_t *) malloc((length + 1) * sizeof(wchar_t));
     if(tgt->s == NULL) return(ERROR);