diff --git a/sexp.c b/sexp.c
index 9ee6037a..4a860fc5 100644
--- a/sexp.c
+++ b/sexp.c
@@ -188,6 +188,7 @@ void sexp_init_context_globals (sexp ctx) {
   sexp_global(ctx, SEXP_G_SYMBOLS) = sexp_make_vector(ctx, sexp_make_fixnum(SEXP_SYMBOL_TABLE_SIZE), SEXP_NULL);
 #endif
   sexp_global(ctx, SEXP_G_OOM_ERROR) = sexp_user_exception(ctx, SEXP_FALSE, "out of memory", SEXP_NULL);
+  sexp_global(ctx, SEXP_G_OOS_ERROR) = sexp_user_exception(ctx, SEXP_FALSE, "out of stack space", SEXP_NULL);
   sexp_global(ctx, SEXP_G_QUOTE_SYMBOL) = sexp_intern(ctx, "quote");
   sexp_global(ctx, SEXP_G_QUASIQUOTE_SYMBOL) = sexp_intern(ctx, "quasiquote");
   sexp_global(ctx, SEXP_G_UNQUOTE_SYMBOL) = sexp_intern(ctx, "unquote");