Index: include/patch.h
===================================================================
--- include/patch.h	(revision 8c8b4e5664e0c1a049b4575d5003752b342481d6)
+++ include/patch.h	(revision 6f49665befe6989838fdd6ecbda8ec8cd9f5e69b)
@@ -38,6 +38,6 @@
 struct	patch	{	/* patch table entry (16 bytes per entry) */
 
-	uint16_t	nextstm;	/* index of next entry in stm chain */
-	uint16_t	prevstm;	/* index of previous entry in stm chain */
+	int16_t		nextstm;	/* index of next entry in stm chain */
+	int16_t		prevstm;	/* index of previous entry in stm chain */
 	uint16_t	defnum;		/* definer */
 	uint16_t	stmnum;		/* stimulus */
@@ -50,5 +50,5 @@
 struct	defent	{	/* definition table entry -- 10 bytes per entry */
 
-	uint16_t	nextdef;	/* index of next in def chain */
+	int16_t		nextdef;	/* index of next in def chain */
 	uint16_t	stm;		/* stimulus */
 	uint16_t	adspec;		/* destination type */