diff --git a/eval.c b/eval.c
index 302e5c94..cdd229d8 100644
--- a/eval.c
+++ b/eval.c
@@ -1011,17 +1011,12 @@ sexp sexp_open_input_file_op (sexp ctx, sexp self, sexp_sint_t n, sexp path) {
   FILE *in;
   int count = 0;
   sexp_assert_type(ctx, sexp_stringp, SEXP_STRING, path);
- loop:
-  in = fopen(sexp_string_data(path), "r");
-  if (!in) {
-#if SEXP_USE_GC_FILE_DESCRIPTORS
-    if (errno == EMFILE && !count++) {
-      sexp_gc(ctx, NULL);
-      goto loop;
-    }
-#endif
+  do {
+    if (count != 0) sexp_gc(ctx, NULL);
+    in = fopen(sexp_string_data(path), "r");
+  } while (!in && sexp_out_of_file_descriptors() && !count++);
+  if (!in)
     return sexp_user_exception(ctx, self, "couldn't open input file", path);
-  }
 #if SEXP_USE_GREEN_THREADS
   fcntl(fileno(in), F_SETFL, O_NONBLOCK);
 #endif
@@ -1032,17 +1027,12 @@ sexp sexp_open_output_file_op (sexp ctx, sexp self, sexp_sint_t n, sexp path) {
   FILE *out;
   int count = 0;
   sexp_assert_type(ctx, sexp_stringp, SEXP_STRING, path);
- loop:
-  out = fopen(sexp_string_data(path), "w");
-  if (!out) {
-#if SEXP_USE_GC_FILE_DESCRIPTORS
-    if (errno == EMFILE && !count++) {
-      sexp_gc(ctx, NULL);
-      goto loop;
-    }
-#endif
+  do {
+    if (count != 0) sexp_gc(ctx, NULL);
+    out = fopen(sexp_string_data(path), "w");
+  } while (!out && sexp_out_of_file_descriptors() && !count++);
+  if (!out)
     return sexp_user_exception(ctx, self, "couldn't open output file", path);
-  }
   return sexp_make_output_port(ctx, out, path);
 }
 
diff --git a/include/chibi/features.h b/include/chibi/features.h
index 1e0cf0f4..0846d313 100644
--- a/include/chibi/features.h
+++ b/include/chibi/features.h
@@ -507,7 +507,7 @@
 #endif
 
 #ifndef SEXP_USE_GC_FILE_DESCRIPTORS
-#define SEXP_USE_GC_FILE_DESCRIPTORS (SEXP_USE_AUTOCLOSE_PORTS &&!SEXP_USE_BOEHM)
+#define SEXP_USE_GC_FILE_DESCRIPTORS (SEXP_USE_AUTOCLOSE_PORTS &&!SEXP_USE_BOEHM && !defined(PLAN9))
 #endif
 
 #ifndef SEXP_USE_2010_EPOCH
diff --git a/include/chibi/sexp.h b/include/chibi/sexp.h
index 9e032aa3..3f30cfa2 100755
--- a/include/chibi/sexp.h
+++ b/include/chibi/sexp.h
@@ -25,9 +25,11 @@ extern "C" {
 #if SEXP_USE_DL
 #include <dlfcn.h>
 #endif
+#if SEXP_USE_GREEN_THREADS || SEXP_USE_GC_FILE_DESCRIPTORS
+#include <errno.h>
+#endif
 #if SEXP_USE_GREEN_THREADS
 #include <sys/time.h>
-#include <errno.h>
 #include <fcntl.h>
 #endif
 #define sexp_isalpha(x) (isalpha(x))
@@ -37,6 +39,12 @@ extern "C" {
 #define sexp_toupper(x) (toupper(x))
 #endif
 
+#if SEXP_USE_GC_FILE_DESCRIPTORS
+#define sexp_out_of_file_descriptors() (errno == EMFILE)
+#else
+#define sexp_out_of_file_descriptors() (0)
+#endif
+
 #ifdef PLAN9
 #include <u.h>
 #include <libc.h>
@@ -430,6 +438,8 @@ void sexp_free(void* ptr);
 
 #if SEXP_USE_BOEHM
 
+#define sexp_gc(ctx, sum)
+
 #define sexp_gc_var(ctx, x, y)       sexp x;
 #define sexp_gc_preserve(ctx, x, y)
 #define sexp_gc_release(ctx, x, y)
@@ -443,6 +453,8 @@ void sexp_free(void* ptr);
 
 #else
 
+SEXP_API sexp sexp_gc(sexp ctx, size_t *sum_freed);
+
 #define sexp_gc_var(ctx, x, y)                  \
   sexp x = SEXP_VOID;                           \
   struct sexp_gc_var_t y = {NULL, NULL};