Index: bin/sh/expand.c
===================================================================
--- bin/sh/expand.c	(revision 275690)
+++ bin/sh/expand.c	(working copy)
@@ -851,6 +851,9 @@
 		if (num > shellparam.nparam)
 			return 0;
 
+		if (num < 0)
+			return 1;
+
 		if (num == 0)
 			ap = arg0;
 		else