diff --git a/vm/backend/tb.c b/vm/backend/tb.c
index cfe5ae5e..81bf18e8 100644
--- a/vm/backend/tb.c
+++ b/vm/backend/tb.c
@@ -38,14 +38,17 @@ size_t vm_tb_ptr_len = 0;
 void **vm_tb_ptr_globals = NULL;
 size_t vm_tb_ptr_alloc = 0;
 
+// void GC_add_roots(void *, void *);
+
 TB_Node *vm_tb_ptr_name(vm_tb_state_t *state, const char *name, void *value) {
-    if (value != NULL) {
-        if (vm_tb_ptr_len + 1 >= vm_tb_ptr_alloc) {
-            vm_tb_ptr_alloc = (vm_tb_ptr_len + 1) * 2;
-            vm_tb_ptr_globals = vm_realloc(vm_tb_ptr_globals, sizeof(void *) * vm_tb_ptr_alloc);
-        }
-        vm_tb_ptr_globals[vm_tb_ptr_len++] = value;
-    }
+    // if (value != NULL) {
+    //     if (vm_tb_ptr_len + 1 >= vm_tb_ptr_alloc) {
+    //         vm_tb_ptr_alloc = (vm_tb_ptr_len + 1) * 2;
+    //         vm_tb_ptr_globals = vm_realloc(vm_tb_ptr_globals, sizeof(void *) * vm_tb_ptr_alloc);
+    //         GC_add_roots(vm_tb_ptr_globals, &vm_tb_ptr_globals[vm_tb_ptr_alloc]);
+    //     }
+    //     vm_tb_ptr_globals[vm_tb_ptr_len++] = value;
+    // }
     return tb_inst_uint(state->fun, TB_TYPE_PTR, (uint64_t)value);
 }
 
diff --git a/vm/config.h b/vm/config.h
index b1315b06..d0fb957a 100644
--- a/vm/config.h
+++ b/vm/config.h
@@ -4,6 +4,7 @@
 
 #define VM_USE_DUMP 1
 #define VM_NO_TAILCALL 1
+#define VM_FORMAT_FLOAT "%.14g"
 
 struct vm_config_t;
 typedef struct vm_config_t vm_config_t;
diff --git a/vm/std/io.c b/vm/std/io.c
index ac6f207a..140f2a69 100644
--- a/vm/std/io.c
+++ b/vm/std/io.c
@@ -100,11 +100,11 @@ void vm_io_print_lit(vm_io_buffer_t *out, vm_std_value_t value) {
             break;
         }
         case VM_TAG_F32: {
-            vm_io_buffer_format(out, "%f", value.value.f32);
+            vm_io_buffer_format(out, VM_FORMAT_FLOAT, value.value.f32);
             break;
         }
         case VM_TAG_F64: {
-            vm_io_buffer_format(out, "%f", value.value.f64);
+            vm_io_buffer_format(out, VM_FORMAT_FLOAT, value.value.f64);
             break;
         }
         case VM_TAG_FFI: {
@@ -172,12 +172,12 @@ void vm_io_debug(vm_io_buffer_t *out, size_t indent, const char *prefix, vm_std_
         }
         case VM_TAG_F32: {
             vm_indent(out, indent, prefix);
-            vm_io_buffer_format(out, "%f\n", value.value.f32);
+            vm_io_buffer_format(out, VM_FORMAT_FLOAT "\n", value.value.f32);
             break;
         }
         case VM_TAG_F64: {
             vm_indent(out, indent, prefix);
-            vm_io_buffer_format(out, "%f\n", value.value.f64);
+            vm_io_buffer_format(out, VM_FORMAT_FLOAT "\n", value.value.f64);
             break;
         }
         case VM_TAG_STR: {
@@ -285,7 +285,7 @@ void vm_io_debug(vm_io_buffer_t *out, size_t indent, const char *prefix, vm_std_
                             .value = p.val_val,
                         };
                         char buf[64];
-                        snprintf(buf, 63, "%f = ", p.key_val.f64);
+                        snprintf(buf, 63, VM_FORMAT_FLOAT " = ", p.key_val.f64);
                         vm_io_debug(out, indent + 1, buf, val, &next);
                         break;
                     }
diff --git a/vm/std/std.c b/vm/std/std.c
index addd6507..bcba9205 100644
--- a/vm/std/std.c
+++ b/vm/std/std.c
@@ -209,11 +209,11 @@ void vm_value_buffer_tostring(vm_io_buffer_t *buf, vm_std_value_t value) {
             break;
         }
         case VM_TAG_F32: {
-            vm_io_buffer_format(buf, "%f", value.value.f32);
+            vm_io_buffer_format(buf, VM_FORMAT_FLOAT, value.value.f32);
             break;
         }
         case VM_TAG_F64: {
-            vm_io_buffer_format(buf, "%f", value.value.f64);
+            vm_io_buffer_format(buf, VM_FORMAT_FLOAT, value.value.f64);
             break;
         }
         case VM_TAG_STR: {