diff --git a/i.c b/i.c
index f9084a0..8b8b40a 100644
--- a/i.c
+++ b/i.c
@@ -3890,6 +3890,16 @@ define_instruction(getenv) {
   gonexti(); 
 }
 
+define_instruction(envvref) {
+  extern const char *environ_ref(int idx);
+  int i; char *s; ckk(ac);
+  i = get_fixnum(ac); /* todo: range-check */
+  s = (char *)environ_ref(i);
+  if (s) ac = string_obj(newstring(s));
+  else ac = bool_obj(0); 
+  gonexti(); 
+}
+
 define_instruction(clock) {
   double d = (double)clock();
   ac = flonum_obj(d);
diff --git a/i.h b/i.h
index b8e379a..c1a1184 100644
--- a/i.h
+++ b/i.h
@@ -519,6 +519,7 @@ declare_instruction(frem,       "F1",           0,  "delete-file",
 declare_instruction(fren,       "F2",           0,  "rename-file",              '2', AUTOGL)
 declare_instruction(argvref,    "Z0",           0,  "%argv-ref",                '1', AUTOGL)
 declare_instruction(getenv,     "Z1",           0,  "get-environment-variable", '1', AUTOGL)
+declare_instruction(envvref,    "Z2",           0,  "%envv-ref",                '1', AUTOGL)
 declare_instruction(clock,      "Z3",           0,  "current-jiffy",            '0', AUTOGL)
 declare_instruction(clops,      "Z4",           0,  "jiffies-per-second",       '0', AUTOGL)
 declare_instruction(cursec,     "Z5",           0,  "current-second",           '0', AUTOGL)
diff --git a/s.c b/s.c
index b931381..be91040 100644
--- a/s.c
+++ b/s.c
@@ -17,6 +17,23 @@ int dirsep = '\\';
 int dirsep = '/';
 #endif
 
+#if defined(WIN32)
+#define sxc_environ _environ
+#elif defined(__linux) || defined(__APPLE__)
+#define sxc_environ environ
+#else /* add more systems? */
+char **sxc_environ = { NULL };
+#endif
+
+extern const char *environ_ref(int idx)
+{
+  const char **pe = sxc_environ;
+  /* be careful with indexing! */
+  if (idx < 0) return NULL;
+  while (idx-- > 0) if (*pe++ == NULL) return NULL;
+  return *pe;
+}
+
 char *s_code[] = {
 
   "S", "let-syntax",