diff --git a/include/chibi/sexp.h b/include/chibi/sexp.h
index 13025024..b464eaaa 100755
--- a/include/chibi/sexp.h
+++ b/include/chibi/sexp.h
@@ -437,9 +437,10 @@ struct sexp_struct {
 #define SEXP_UNDEF  SEXP_MAKE_IMMEDIATE(5) /* internal use */
 #define SEXP_CLOSE  SEXP_MAKE_IMMEDIATE(6) /* internal use */
 #define SEXP_RAWDOT SEXP_MAKE_IMMEDIATE(7) /* internal use */
-#define SEXP_STRING_OPORT SEXP_MAKE_IMMEDIATE(8) /* internal use */
+#define SEXP_STRING_OPORT SEXP_MAKE_IMMEDIATE(8)  /* internal use */
+#define SEXP_TRAMPOLINE   SEXP_MAKE_IMMEDIATE(9)  /* internal use */
 #if SEXP_USE_OBJECT_BRACE_LITERALS
-#define SEXP_CLOSE_BRACE SEXP_MAKE_IMMEDIATE(9) /* internal use */
+#define SEXP_CLOSE_BRACE  SEXP_MAKE_IMMEDIATE(10) /* internal use */
 #endif
 
 #if SEXP_USE_LIMITED_MALLOC
@@ -878,6 +879,10 @@ SEXP_API sexp sexp_make_unsigned_integer(sexp ctx, sexp_luint_t x);
 #define sexp_exception_procedure(x) (sexp_field(x, exception, SEXP_EXCEPTION, procedure))
 #define sexp_exception_source(x)    (sexp_field(x, exception, SEXP_EXCEPTION, source))
 
+#define sexp_trampolinep(x) (sexp_exceptionp(x) && sexp_exception_kind(x) == SEXP_TRAMPOLINE)
+#define sexp_trampoline_procedure(x) sexp_exception_procedure(x)
+#define sexp_trampoline_args(x) sexp_exception_irritants(x)
+
 #define sexp_cpointer_freep(x)      (sexp_freep(x))
 #define sexp_cpointer_length(x)     (sexp_cpointer_field(x, length))
 #define sexp_cpointer_body(x)       (sexp_cpointer_field(x, body))
@@ -1194,7 +1199,6 @@ enum sexp_context_globals {
 #define sexp_push_char(x, c, p) (ungetc(c, sexp_port_stream(p)))
 #define sexp_write_char(x, c, p) (putc(c, sexp_port_stream(p)))
 #define sexp_write_string(x, s, p) (fputs(s, sexp_port_stream(p)))
-#define sexp_printf(x, p, ...) (fprintf(sexp_port_stream(p), __VA_ARGS__))
 #define sexp_flush(x, p) (fflush(sexp_port_stream(p)))
 
 #else
@@ -1293,6 +1297,7 @@ SEXP_API sexp sexp_print_exception_op (sexp ctx, sexp self, sexp_sint_t n, sexp
 SEXP_API sexp sexp_stack_trace_op (sexp ctx, sexp self, sexp_sint_t n, sexp out);
 SEXP_API sexp sexp_apply (sexp context, sexp proc, sexp args);
 SEXP_API sexp sexp_apply1 (sexp ctx, sexp f, sexp x);
+SEXP_API sexp sexp_make_trampoline (sexp ctx, sexp proc, sexp args);
 SEXP_API sexp sexp_make_foreign (sexp ctx, const char *name, int num_args, int flags, sexp_proc1 f, sexp data);
 SEXP_API void sexp_init(void);
 
diff --git a/vm.c b/vm.c
index 24e620fe..a5d98328 100644
--- a/vm.c
+++ b/vm.c
@@ -662,6 +662,10 @@ static sexp make_opcode_procedure (sexp ctx, sexp op, sexp_uint_t i) {
 
 /*********************** the virtual machine **************************/
 
+sexp sexp_make_trampoline (sexp ctx, sexp proc, sexp args) {
+  return sexp_make_exception(ctx, SEXP_TRAMPOLINE, SEXP_FALSE, args, proc, SEXP_FALSE);
+}
+
 #if SEXP_USE_GROW_STACK
 static int sexp_grow_stack (sexp ctx, int min_size) {
   sexp stack, old_stack = sexp_context_stack(ctx), *from, *to;
@@ -772,20 +776,20 @@ static int sexp_check_type(sexp ctx, sexp a, sexp b) {
 }
 
 #if SEXP_USE_GREEN_THREADS
-#define sexp_fcall_return(x, i)                         \
-  if (sexp_exceptionp(x)) {                             \
-    if (x == sexp_global(ctx, SEXP_G_IO_BLOCK_ERROR)) { \
-      fuel = 0; ip--; goto loop;                        \
-    } else {                                            \
-      top -= i;                                         \
-      _ARG1 = x;                                        \
-      ip += sizeof(sexp);                               \
-      goto call_error_handler;                          \
-    }                                                   \
-  } else {                                              \
-    top -= i;                                           \
-    _ARG1 = x;                                          \
-    ip += sizeof(sexp);                                 \
+#define sexp_fcall_return(x, i)                             \
+  if (sexp_exceptionp(x)) {                                 \
+    if (x == sexp_global(ctx, SEXP_G_IO_BLOCK_ERROR)) {     \
+      fuel = 0; ip--; goto loop;                            \
+    } else {                                                \
+      top -= i;                                             \
+      _ARG1 = x;                                            \
+      ip += sizeof(sexp);                                   \
+      goto call_error_handler;                              \
+    }                                                       \
+  } else {                                                  \
+    top -= i;                                               \
+    _ARG1 = x;                                              \
+    ip += sizeof(sexp);                                     \
   }
 #else
 #define sexp_fcall_return(x, i)                                 \
@@ -912,6 +916,12 @@ sexp sexp_apply (sexp ctx, sexp proc, sexp args) {
       sexp_exception_procedure(_ARG1) = self;
   case SEXP_OP_RAISE:
     sexp_context_top(ctx) = top;
+    if (sexp_trampolinep(_ARG1)) {
+      tmp1 = sexp_trampoline_procedure(_ARG1);
+      tmp2 = sexp_trampoline_args(_ARG1);
+      top--;
+      goto apply1;
+    }
     tmp1 = sexp_parameter_ref(ctx, sexp_global(ctx, SEXP_G_ERR_HANDLER));
     sexp_context_last_fp(ctx) = fp;
     if (! sexp_procedurep(tmp1))