diff --git a/extlib/benz/codegen.c b/extlib/benz/codegen.c
index 39b4bfc4..f3d34730 100644
--- a/extlib/benz/codegen.c
+++ b/extlib/benz/codegen.c
@@ -8,6 +8,7 @@
 #include "picrin/proc.h"
 #include "picrin/lib.h"
 #include "picrin/macro.h"
+#include "picrin/dict.h"
 
 #if PIC_NONE_IS_FALSE
 # define OP_PUSHNONE OP_PUSHFALSE
@@ -63,7 +64,7 @@ static analyze_state *
 new_analyze_state(pic_state *pic)
 {
   analyze_state *state;
-  xh_entry *it;
+  pic_sym sym;
 
   state = pic_alloc(pic, sizeof(analyze_state));
   state->pic = pic;
@@ -101,8 +102,7 @@ new_analyze_state(pic_state *pic)
   /* push initial scope */
   push_scope(state, pic_nil_value());
 
-  for (it = xh_begin(&pic->globals); it != NULL; it = xh_next(it)) {
-    pic_sym sym = xh_key(it, pic_sym);
+  pic_dict_for_each (sym, pic->globals) {
     xv_push(&state->scope->locals, &sym);
   }
 
diff --git a/extlib/benz/gc.c b/extlib/benz/gc.c
index e209ddda..88d2df5a 100644
--- a/extlib/benz/gc.c
+++ b/extlib/benz/gc.c
@@ -549,13 +549,13 @@ gc_mark_phase(pic_state *pic)
   }
 
   /* global variables */
-  for (it = xh_begin(&pic->globals); it != NULL; it = xh_next(it)) {
-    gc_mark(pic, xh_val(it, pic_value));
+  if (pic->globals) {
+    gc_mark_object(pic, (struct pic_object *)pic->globals);
   }
 
   /* macro objects */
-  for (it = xh_begin(&pic->macros); it != NULL; it = xh_next(it)) {
-    gc_mark_object(pic, xh_val(it, struct pic_object *));
+  if (pic->macros) {
+    gc_mark_object(pic, (struct pic_object *)pic->macros);
   }
 
   /* error object */
diff --git a/extlib/benz/include/picrin.h b/extlib/benz/include/picrin.h
index 418cff2c..b424ac65 100644
--- a/extlib/benz/include/picrin.h
+++ b/extlib/benz/include/picrin.h
@@ -116,8 +116,8 @@ typedef struct {
   int sym_cnt;
   int uniq_sym_cnt;
 
-  xhash globals;
-  xhash macros;
+  struct pic_dict *globals;
+  struct pic_dict *macros;
   pic_value libs;
   xhash attrs;
 
diff --git a/extlib/benz/include/picrin/dict.h b/extlib/benz/include/picrin/dict.h
index 8d6077af..cfbd4855 100644
--- a/extlib/benz/include/picrin/dict.h
+++ b/extlib/benz/include/picrin/dict.h
@@ -19,6 +19,13 @@ struct pic_dict {
 
 struct pic_dict *pic_make_dict(pic_state *);
 
+#define pic_dict_for_each(sym, dict)                    \
+  pic_dict_for_each_helper_((sym), PIC_GENSYM(tmp), (dict))
+#define pic_dict_for_each_helper_(var, tmp, dict)                       \
+  for (xh_entry *tmp = xh_begin(&dict->hash);                           \
+       (tmp && ((var = xh_key(tmp, pic_sym)), 1));                      \
+       tmp = xh_next(tmp))
+
 pic_value pic_dict_ref(pic_state *, struct pic_dict *, pic_sym);
 void pic_dict_set(pic_state *, struct pic_dict *, pic_sym, pic_value);
 void pic_dict_del(pic_state *, struct pic_dict *, pic_sym);
diff --git a/extlib/benz/macro.c b/extlib/benz/macro.c
index d5604635..7e1c7b36 100644
--- a/extlib/benz/macro.c
+++ b/extlib/benz/macro.c
@@ -49,18 +49,16 @@ pic_find_rename(pic_state *pic, struct pic_senv *senv, pic_sym sym, pic_sym *ren
 static void
 define_macro(pic_state *pic, pic_sym rename, struct pic_proc *mac)
 {
-  xh_put_int(&pic->macros, rename, &mac);
+  pic_dict_set(pic, pic->macros, rename, pic_obj_value(mac));
 }
 
 static struct pic_proc *
 find_macro(pic_state *pic, pic_sym rename)
 {
-  xh_entry *e;
-
-  if ((e = xh_get_int(&pic->macros, rename)) == NULL) {
+  if (! pic_dict_has(pic, pic->macros, rename)) {
     return NULL;
   }
-  return xh_val(e, struct pic_proc *);
+  return pic_proc_ptr(pic_dict_ref(pic, pic->macros, rename));
 }
 
 static pic_sym
diff --git a/extlib/benz/state.c b/extlib/benz/state.c
index 3f32e1c5..7271c8e7 100644
--- a/extlib/benz/state.c
+++ b/extlib/benz/state.c
@@ -10,6 +10,7 @@
 #include "picrin/cont.h"
 #include "picrin/port.h"
 #include "picrin/error.h"
+#include "picrin/dict.h"
 
 void pic_init_core(pic_state *);
 
@@ -54,10 +55,10 @@ pic_open(int argc, char *argv[], char **envp)
   pic->uniq_sym_cnt = 0;
 
   /* global variables */
-  xh_init_int(&pic->globals, sizeof(pic_value));
+  pic->globals = NULL;
 
   /* macros */
-  xh_init_int(&pic->macros, sizeof(struct pic_macro *));
+  pic->macros = NULL;
 
   /* attributes */
   xh_init_ptr(&pic->attrs, sizeof(struct pic_dict *));
@@ -155,6 +156,10 @@ pic_open(int argc, char *argv[], char **envp)
   R(rCOND_EXPAND, "cond-expand");
   pic_gc_arena_restore(pic, ai);
 
+  /* root tables */
+  pic->globals = pic_make_dict(pic);
+  pic->macros = pic_make_dict(pic);
+
   /* root block */
   pic->wind = pic_alloc(pic, sizeof(struct pic_winder));
   pic->wind->prev = NULL;
@@ -198,8 +203,8 @@ pic_close(pic_state *pic)
   pic->xp = pic->xpbase;
   pic->arena_idx = 0;
   pic->err = pic_undef_value();
-  xh_clear(&pic->globals);
-  xh_clear(&pic->macros);
+  pic->globals = NULL;
+  pic->macros = NULL;
   xh_clear(&pic->attrs);
   pic->features = pic_nil_value();
   pic->libs = pic_nil_value();
@@ -222,8 +227,6 @@ pic_close(pic_state *pic)
 
   /* free global stacks */
   xh_destroy(&pic->syms);
-  xh_destroy(&pic->globals);
-  xh_destroy(&pic->macros);
   xh_destroy(&pic->attrs);
 
   /* free GC arena */
diff --git a/extlib/benz/vm.c b/extlib/benz/vm.c
index ea4821e2..0e5bc7fd 100644
--- a/extlib/benz/vm.c
+++ b/extlib/benz/vm.c
@@ -442,7 +442,7 @@ pic_define_noexport(pic_state *pic, const char *name, pic_value val)
     pic_warn(pic, "redefining global");
   }
 
-  xh_put_int(&pic->globals, rename, &val);
+  pic_dict_set(pic, pic->globals, rename, val);
 }
 
 void
@@ -464,7 +464,7 @@ pic_ref(pic_state *pic, struct pic_lib *lib, const char *name)
     pic_errorf(pic, "symbol \"%s\" not defined in library ~s", name, lib->name);
   }
 
-  return xh_val(xh_get_int(&pic->globals, rename), pic_value);
+  return pic_dict_ref(pic, pic->globals, rename);
 }
 
 void
@@ -478,7 +478,7 @@ pic_set(pic_state *pic, struct pic_lib *lib, const char *name, pic_value val)
     pic_errorf(pic, "symbol \"%s\" not defined in library ~s", name, lib->name);
   }
 
-  xh_put_int(&pic->globals, rename, &val);
+  pic_dict_set(pic, pic->globals, rename, val);
 }
 
 pic_value
@@ -766,19 +766,17 @@ pic_apply(pic_state *pic, struct pic_proc *proc, pic_value args)
       NEXT;
     }
     CASE(OP_GREF) {
-      xh_entry *e;
-
-      if ((e = xh_get_int(&pic->globals, c.u.i)) == NULL) {
+      if (! pic_dict_has(pic, pic->globals, c.u.i)) {
         pic_errorf(pic, "logic flaw; reference to uninitialized global variable: %s", pic_symbol_name(pic, c.u.i));
       }
-      PUSH(xh_val(e, pic_value));
+      PUSH(pic_dict_ref(pic, pic->globals, c.u.i));
       NEXT;
     }
     CASE(OP_GSET) {
       pic_value val;
 
       val = POP();
-      xh_put_int(&pic->globals, c.u.i, &val);
+      pic_dict_set(pic, pic->globals, c.u.i, val);
       NEXT;
     }
     CASE(OP_LREF) {