diff --git a/Makefile b/Makefile
index ef54622f..457b0e5c 100644
--- a/Makefile
+++ b/Makefile
@@ -72,7 +72,7 @@ valgrind: $(DST_TARGET)
 	@ valgrind --leak-check=full -v ./$(DST_TARGET)
 
 test: $(DST_TARGET)
-	@ ./$(DST_TARGET) dsttest/suite0.dst
+	@ ./$(DST_TARGET) --gcinterval=0 dsttest/suite0.dst
 
 valtest: $(DST_TARGET)
 	valgrind --leak-check=full -v ./$(DST_TARGET) dsttests/basic.dst
diff --git a/client/main.c b/client/main.c
index 8a7192f6..1501b2cf 100644
--- a/client/main.c
+++ b/client/main.c
@@ -176,7 +176,7 @@ static void runfile(const uint8_t *src, int32_t len) {
 }
 
 int main(int argc, char **argv) {
-    int status = -1;
+    int status = 0;
     int i;
     int fileRead = 0;
     uint32_t gcinterval = 0x10000;
diff --git a/core/compile_specials.c b/core/compile_specials.c
index 037ba922..d54cdbd4 100644
--- a/core/compile_specials.c
+++ b/core/compile_specials.c
@@ -491,6 +491,9 @@ DstSlot dstc_fn(DstFopts opts, int32_t argn, const Dst *argv) {
     if (varargs) def->flags |= DST_FUNCDEF_FLAG_VARARG;
     defindex = dstc_addfuncdef(c, def);
 
+    /* Ensure enough slots for vararg function. */
+    if (arity + varargs > def->slotcount) def->slotcount = arity + varargs;
+
     /* Instantiate closure */
     ret.flags = 0;
     ret.envindex = 0;
diff --git a/core/fiber.c b/core/fiber.c
index 7abe4932..1f501881 100644
--- a/core/fiber.c
+++ b/core/fiber.c
@@ -45,7 +45,7 @@ DstFiber *dst_fiber_reset(DstFiber *fiber) {
     fiber->frame = 0;
     fiber->stackstart = DST_FRAME_SIZE;
     fiber->stacktop = DST_FRAME_SIZE;
-    fiber->status = DST_FIBER_PENDING;
+    fiber->status = DST_FIBER_NEW;
     fiber->parent = NULL;
     return fiber;
 }
diff --git a/core/stl.c b/core/stl.c
index 30c1a710..07aa20b9 100644
--- a/core/stl.c
+++ b/core/stl.c
@@ -23,6 +23,15 @@
 #include <dst/dst.h>
 #include <dst/dststl.h>
 
+int dst_stl_exit(int32_t argn, Dst *argv, Dst *ret) {
+    (void)ret;
+    int32_t exitcode = 0;
+    if (argn > 0) {
+        exitcode = dst_hash(argv[0]);
+    }
+    exit(exitcode);
+}
+
 int dst_stl_print(int32_t argn, Dst *argv, Dst *ret) {
     (void)ret;
 
@@ -210,6 +219,37 @@ int dst_stl_get(int32_t argn, Dst *argv, Dst *ret) {
     return 0;
 }
 
+int dst_stl_status(int32_t argn, Dst *argv, Dst *ret) {
+    const char *status;
+    if (argn != 1) {
+        *ret = dst_cstringv("expected 1 argument");
+        return 1;
+    }
+    if (!dst_checktype(argv[0], DST_FIBER)) {
+        *ret = dst_cstringv("expected fiber");
+        return 1;
+    }
+    switch(dst_unwrap_fiber(argv[0])->status) {
+        case DST_FIBER_PENDING:
+            status = "pending";
+            break;
+        case DST_FIBER_NEW:
+            status = "new";
+            break;
+        case DST_FIBER_ALIVE:
+            status = "alive";
+            break;
+        case DST_FIBER_DEAD:
+            status = "dead";
+            break;
+        case DST_FIBER_ERROR:
+            status = "error";
+            break;
+    }
+    *ret = dst_cstringv(status);
+    return 0;
+}
+
 int dst_stl_put(int32_t argn, Dst *argv, Dst *ret) {
     Dst ds, key, value;
     if (argn < 3) {
@@ -284,6 +324,7 @@ static DstReg stl[] = {
     {"tuple", dst_stl_tuple},
     {"struct", dst_stl_struct},
     {"fiber", dst_stl_fiber},
+    {"status", dst_stl_status},
     {"buffer", dst_stl_buffer},
     {"gensym", dst_stl_gensym},
     {"asm", dst_stl_asm},
@@ -325,7 +366,8 @@ static DstReg stl[] = {
     {"fopen", dst_stl_fileopen},
     {"fclose", dst_stl_fileclose},
     {"fwrite", dst_stl_filewrite},
-    {"fread", dst_stl_fileread}
+    {"fread", dst_stl_fileread},
+    {"exit!", dst_stl_exit}
 };
 
 Dst dst_loadstl(int flags) {
diff --git a/core/string.c b/core/string.c
index 3a469aaa..c4749a8f 100644
--- a/core/string.c
+++ b/core/string.c
@@ -121,7 +121,7 @@ static const uint8_t *real_to_string(double x) {
     return dst_string(buf, real_to_string_impl(buf, x));
 }
 
-static int32_t integer_to_string_impl(uint8_t *buf, int64_t x) {
+static int32_t integer_to_string_impl(uint8_t *buf, int32_t x) {
     int neg = 0;
     uint8_t *hi, *low;
     int32_t count = 0;
@@ -151,12 +151,12 @@ static int32_t integer_to_string_impl(uint8_t *buf, int64_t x) {
     return count;
 }
 
-static void integer_to_string_b(DstBuffer *buffer, int64_t x) {
+static void integer_to_string_b(DstBuffer *buffer, int32_t x) {
     dst_buffer_extra(buffer, DST_BUFSIZE);
     buffer->count += integer_to_string_impl(buffer->data + buffer->count, x);
 }
 
-static const uint8_t *integer_to_string(int64_t x) {
+static const uint8_t *integer_to_string(int32_t x) {
     uint8_t buf[DST_BUFSIZE];
     return dst_string(buf, integer_to_string_impl(buf, x));
 }
@@ -641,7 +641,7 @@ const uint8_t *dst_formatc(const char *format, ...) {
                         real_to_string_b(bufp, va_arg(args, double));
                         break;
                     case 'd': 
-                        integer_to_string_b(bufp, va_arg(args, int64_t));
+                        integer_to_string_b(bufp, va_arg(args, int32_t));
                         break;
                     case 'S':
                     {
@@ -653,7 +653,7 @@ const uint8_t *dst_formatc(const char *format, ...) {
                         dst_buffer_push_cstring(bufp, va_arg(args, const char *));
                         break;
                     case 'c':
-                        dst_buffer_push_u8(bufp, va_arg(args, int64_t));
+                        dst_buffer_push_u8(bufp, va_arg(args, long));
                         break;
                     case 'v':
                     {
diff --git a/core/strtod.c b/core/strtod.c
index 00630f48..bc7d7b6a 100644
--- a/core/strtod.c
+++ b/core/strtod.c
@@ -123,7 +123,8 @@ static double convert(
         : ldexp(mantissa, exponent2);
 }
 
-/* Result of scanning a number source */
+/* Result of scanning a number source string. Will be further processed
+ * depending on the desired resultant type. */
 struct DstScanRes {
     uint64_t mant;
     int32_t ex;
diff --git a/core/value.c b/core/value.c
index ff4d070c..9c69466f 100644
--- a/core/value.c
+++ b/core/value.c
@@ -67,9 +67,13 @@ int32_t dst_hash(Dst x) {
     int32_t hash = 0;
     switch (dst_type(x)) {
     case DST_NIL:
+        hash = 0;
+        break;
     case DST_FALSE:
+        hash = 1;
+        break;
     case DST_TRUE:
-        hash = dst_type(x);
+        hash = 2;
         break;
     case DST_STRING:
     case DST_SYMBOL:
@@ -81,6 +85,8 @@ int32_t dst_hash(Dst x) {
     case DST_STRUCT:
         hash = dst_struct_hash(dst_unwrap_struct(x));
         break;
+    case DST_INTEGER:
+        hash = dst_unwrap_integer(x);
     default:
         if (sizeof(double) == sizeof(void *)) {
             /* Assuming 8 byte pointer */
diff --git a/core/vm.c b/core/vm.c
index 3cd67ced..f7ced1a0 100644
--- a/core/vm.c
+++ b/core/vm.c
@@ -532,6 +532,7 @@ static int dst_continue(Dst *returnreg) {
 
         case DOP_TRANSFER:
         {
+            int status;
             DstFiber *nextfiber;
             DstStackFrame *frame = dst_stack_frame(stack);
             Dst temp = stack[oparg(2, 0xFF)];
@@ -547,14 +548,31 @@ static int dst_continue(Dst *returnreg) {
                 *returnreg = retreg;
                 return 0;
             }
-            vm_assert(nextfiber->status == DST_FIBER_PENDING, "can only transfer to pending fiber");
+            status = nextfiber->status;
+            vm_assert(status == DST_FIBER_PENDING ||
+                    status == DST_FIBER_NEW, "can only transfer to new or pending fiber");
             frame->pc = pc;
             dst_vm_fiber->status = DST_FIBER_PENDING;
             dst_vm_fiber = nextfiber;
             vm_init_fiber_state();
-            stack[oparg(1, 0xFF)] = retreg;
-            pc++;
-            vm_next();
+            if (status == DST_FIBER_PENDING) {
+                /* The next fiber is currently on a transfer instruction. */
+                stack[oparg(1, 0xFF)] = retreg;
+                pc++;
+            } else {
+                /* The next fiber is new and is on the first instruction */
+                if ((func->def->flags & DST_FUNCDEF_FLAG_VARARG) &&
+                        !func->def->arity) {
+                    /* Fully var arg function */
+                    Dst *tup = dst_tuple_begin(1);
+                    tup[0] = retreg;
+                    stack[0] = dst_wrap_tuple(dst_tuple_end(tup));
+                } else if (func->def->arity) {
+                    /* Non zero arity function */
+                    stack[0] = retreg;
+                }
+            }
+            vm_checkgc_next();
         }
 
         case DOP_PUT:
@@ -569,7 +587,7 @@ static int dst_continue(Dst *returnreg) {
                 stack[oparg(2, 0xFF)],
                 oparg(3, 0xFF));
         ++pc;
-        vm_next();
+        vm_checkgc_next();
 
         case DOP_GET:
         stack[oparg(1, 0xFF)] = dst_get(
diff --git a/dsttest/suite0.dst b/dsttest/suite0.dst
index d0cc0d7e..699cc2a1 100644
--- a/dsttest/suite0.dst
+++ b/dsttest/suite0.dst
@@ -112,6 +112,13 @@
 
 # Fiber tests
 
+(def error (asm '{
+  arity 1
+  bytecode [
+    (error 0)
+  ]
+}))
+
 (def afiber (fiber (fn [x]
 	(error (string "hello, " x)))))
 
@@ -124,10 +131,10 @@
 
 (def t (fiber (fn [] (transfer nil 1) (transfer nil 2) 3)))
 
-(assert (= 1 (transfer t)) "initial transfer to new thread")
-(assert (= 2 (transfer t)) "second transfer to thread")
-(assert (= 3 (transfer t)) "return from thread")
-(assert (= (status t) "dead") "finished thread is dead")
+(assert (= 1 (transfer t)) "initial transfer to new fiber")
+(assert (= 2 (transfer t)) "second transfer to fiber")
+(assert (= 3 (transfer t)) "return from fiber")
+(assert (= (status t) "dead") "finished fiber is dead")
 
 # Var arg tests
 
@@ -139,13 +146,6 @@
   ] 
 }))
 
-(def error (asm '{
-  arity 1
-  bytecode [
-    (error 0)
-  ]
-}))
-
 (def vargf (fn [more] (apply + more)))
 
 (assert (= 0 (vargf [])) "var arg no arguments")
@@ -169,4 +169,4 @@
 # report
 
 (print "\n" num-tests-passed " of " num-tests-run " tests passed\n")
-(if (not (= num-tests-passed num-tests-run)) (exit! 1))
+(if (not= num-tests-passed num-tests-run) (exit! 1))
diff --git a/include/dst/dsttypes.h b/include/dst/dsttypes.h
index acf2b44b..038bcc01 100644
--- a/include/dst/dsttypes.h
+++ b/include/dst/dsttypes.h
@@ -319,7 +319,8 @@ struct DstFiber {
     int32_t stacktop; /* Top of stack. Where values are pushed and popped from. */
     int32_t capacity;
     enum {
-        DST_FIBER_PENDING = 0,
+        DST_FIBER_PENDING,
+        DST_FIBER_NEW,
         DST_FIBER_ALIVE,
         DST_FIBER_DEAD,
         DST_FIBER_ERROR