diff --git a/include/chibi/features.h b/include/chibi/features.h
index 5354c357..1021fb62 100644
--- a/include/chibi/features.h
+++ b/include/chibi/features.h
@@ -660,6 +660,8 @@
 #define strcasestr cistrstr
 #define round(x) floor((x)+0.5)
 #define trunc(x) floor((x)+0.5*(((x)<0)?1:0))
+#define isinf(x) (isInf(x,1) || isInf(x,-1))
+#define isnan(x) isNaN(x)
 #elif defined(_WIN32)
 #define snprintf(buf, len, fmt, val) sprintf(buf, fmt, val)
 #define strcasecmp lstrcmpi
@@ -674,6 +676,10 @@
 #define sexp_pos_infinity (DBL_MAX*DBL_MAX)
 #define sexp_neg_infinity -sexp_pos_infinity
 #define sexp_nan log(-2)
+#elif PLAN9
+#define sexp_pos_infinity Inf(1)
+#define sexp_neg_infinity Inf(-1)
+#define sexp_nan NaN()
 #else
 #define sexp_pos_infinity (1.0/0.0)
 #define sexp_neg_infinity -sexp_pos_infinity
diff --git a/include/chibi/sexp.h b/include/chibi/sexp.h
index 1526656e..60e93a24 100755
--- a/include/chibi/sexp.h
+++ b/include/chibi/sexp.h
@@ -1062,7 +1062,7 @@ SEXP_API sexp sexp_make_unsigned_integer(sexp ctx, sexp_luint_t x);
 #define sexp_context_exception(x) (sexp_vector_ref(sexp_context_specific(x), SEXP_SIX))
 
 #if SEXP_USE_ALIGNED_BYTECODE
-#define sexp_context_align_pos(ctx) sexp_context_pos(ctx) = sexp_word_align(sexp_context_pos(ctx))
+#define sexp_context_align_pos(ctx) sexp_context_pos(ctx) = (sexp)sexp_word_align((sexp_uint_t)sexp_context_pos(ctx))
 #else
 #define sexp_context_align_pos(ctx)
 #endif
diff --git a/main.c b/main.c
index 47b11119..6c3cf93f 100644
--- a/main.c
+++ b/main.c
@@ -511,4 +511,5 @@ int main (int argc, char **argv) {
   sexp_scheme_init();
   run_main(argc, argv);
   exit_success();
+  return 0;
 }