diff --git a/coregrind/vg_constants.h b/coregrind/vg_constants.h
index 43f7044..7416f9d 100644
--- a/coregrind/vg_constants.h
+++ b/coregrind/vg_constants.h
@@ -65,6 +65,9 @@
 /* Offset of code in a TCEntry */
 #define VG_CODE_OFFSET		(8 + VG_MAX_JUMPS * 2)
 
+/* Client address space segment limit descriptor entry */
+#define VG_POINTERCHECK_SEGIDX	1
+
 /* Debugging hack for assembly code ... sigh. */
 #if 0
 #define OYNK(nnn) pushal;  pushl $nnn; call VG_(oynk) ; addl $4,%esp; popal
@@ -90,6 +93,29 @@
 /* Assembly code stubs make this request */
 #define VG_USERREQ__SIGNAL_RETURNS          0x4001
 
+/* Various environment variables we pay attention to */
+
+/* The directory we look for all our auxillary files in */
+#define VALGRINDLIB	"VALGRINDLIB"
+
+/* Additional command-line arguments; they are overridden by actual
+   command-line option.  Each argument is separated by spaces.  There
+   is no quoting mechanism.
+ */
+#define VALGRINDOPTS	"VALGRIND_OPTS"
+
+/* If this variable is present in the environment, then valgrind will
+   not parse the command line for options at all; all options come
+   from this variable.  Arguments are terminated by ^A (\001).  There
+   is no quoting mechanism.
+
+   This variable is not expected to be set by anything other than
+   Valgrind itself, as part of its handling of execve with
+   --trace-children=yes.  This variable should not be present in the
+   client environment.
+ */
+#define VALGRINDCLO	"_VALGRIND_CLO"
+
 #endif /* ndef __VG_CONSTANTS_H */
 
 /*--------------------------------------------------------------------*/