Index: generic/nsf.c
===================================================================
diff -u -re82e7006322a3b8b65f4c050e0b4846faa3e2e6d -r057a338bac37aaa2458592037e45ef36f3b71c4b
--- generic/nsf.c	(.../nsf.c)	(revision e82e7006322a3b8b65f4c050e0b4846faa3e2e6d)
+++ generic/nsf.c	(.../nsf.c)	(revision 057a338bac37aaa2458592037e45ef36f3b71c4b)
@@ -11674,7 +11674,7 @@
     }
     paramPtr->flags |= NSF_ARG_SLOTINITIALIZE;
 
-  } else if ((dotdot = strnstr(option, "..", optionLength))) {
+  } else if ((dotdot = strnstr(option, "..", optionLength-1))) {
     /* check lower bound */
     if (*option == '0') {
       paramPtr->flags |= NSF_ARG_ALLOW_EMPTY;