diff --git a/include/picrin.h b/include/picrin.h
index 4c6d63b3..94fc9648 100644
--- a/include/picrin.h
+++ b/include/picrin.h
@@ -87,9 +87,6 @@ typedef struct {
   pic_value lib_tbl;
   struct pic_lib *lib;
 
-  pic_value *pool;
-  size_t plen, pcapa;
-
   jmp_buf *jmp;
   const char *errmsg;
 
diff --git a/include/picrin/irep.h b/include/picrin/irep.h
index 857948b8..3238694c 100644
--- a/include/picrin/irep.h
+++ b/include/picrin/irep.h
@@ -65,7 +65,8 @@ struct pic_irep {
   unsigned *cv_tbl, cv_num;
   bool varg;
   struct pic_irep **irep;
-  size_t clen, ilen;
+  pic_value *pool;
+  size_t clen, ilen, plen;
 };
 
 void pic_dump_irep(pic_state *, struct pic_irep *);
diff --git a/src/codegen.c b/src/codegen.c
index a45599a0..091593c0 100644
--- a/src/codegen.c
+++ b/src/codegen.c
@@ -33,6 +33,7 @@ new_irep(pic_state *pic)
   irep->localc = -1;
   irep->varg = false;
   irep->irep = NULL;
+  irep->pool = NULL;
   return irep;
 }
 
@@ -44,7 +45,7 @@ typedef struct codegen_scope {
   bool varg;
   /* local variables are 1-indexed, 0 is reserved for the callee */
   struct xhash *local_tbl;
-  /* rest args variable is counted at localc */
+  /* rest args variable is counted by localc */
   size_t argc, localc;
   /* if local var i is captured, then dirty_flags[i] == 1 */
   int *dirty_flags;
@@ -54,6 +55,9 @@ typedef struct codegen_scope {
   /* child ireps */
   struct pic_irep **irep;
   size_t ilen, icapa;
+  /* constant object pool */
+  pic_value *pool;
+  size_t plen, pcapa;
 
   struct codegen_scope *up;
 } codegen_scope;
@@ -76,6 +80,9 @@ new_global_scope(pic_state *pic)
   scope->irep = (struct pic_irep **)pic_calloc(pic, PIC_IREP_SIZE, sizeof(struct pic_irep *));
   scope->ilen = 0;
   scope->icapa = PIC_IREP_SIZE;
+  scope->pool = (pic_value *)pic_calloc(pic, PIC_POOL_SIZE, sizeof(pic_value));
+  scope->plen = 0;
+  scope->pcapa = PIC_POOL_SIZE;
 
   return scope;
 }
@@ -122,6 +129,10 @@ new_local_scope(pic_state *pic, pic_value args, codegen_scope *scope)
   new_scope->ilen = 0;
   new_scope->icapa = PIC_IREP_SIZE;
 
+  new_scope->pool = (pic_value *)pic_calloc(pic, PIC_POOL_SIZE, sizeof(pic_value));
+  new_scope->plen = 0;
+  new_scope->pcapa = PIC_POOL_SIZE;
+
   return new_scope;
 }
 
@@ -446,11 +457,11 @@ codegen(codegen_state *state, pic_value obj, bool tailpos)
 	  pic_error(pic, "syntax error");
 	}
 
-	pidx = pic->plen++;
-	if (pidx >= pic->pcapa) {
+	pidx = scope->plen++;
+	if (pidx >= scope->pcapa) {
 	  pic_abort(pic, "constant pool overflow");
 	}
-	pic->pool[pidx] = pic_car(pic, pic_cdr(pic, obj));
+	scope->pool[pidx] = pic_car(pic, pic_cdr(pic, obj));
 	scope->code[scope->clen].insn = OP_PUSHCONST;
 	scope->code[scope->clen].u.i = pidx;
 	scope->clen++;
@@ -682,11 +693,11 @@ codegen(codegen_state *state, pic_value obj, bool tailpos)
   case PIC_TT_VECTOR:
   case PIC_TT_BLOB: {
     int pidx;
-    pidx = pic->plen++;
-    if (pidx >= pic->pcapa) {
+    pidx = scope->plen++;
+    if (pidx >= scope->pcapa) {
       pic_abort(pic, "constant pool overflow");
     }
-    pic->pool[pidx] = obj;
+    scope->pool[pidx] = obj;
     scope->code[scope->clen].insn = OP_PUSHCONST;
     scope->code[scope->clen].u.i = pidx;
     scope->clen++;
@@ -855,6 +866,8 @@ codegen_lambda(codegen_state *state, pic_value obj)
     irep->clen = state->scope->clen;
     irep->irep = pic_realloc(pic, state->scope->irep, sizeof(struct pic_irep *) * state->scope->ilen);
     irep->ilen = state->scope->ilen;
+    irep->pool = pic_realloc(pic, state->scope->pool, sizeof(pic_value) * state->scope->plen);
+    irep->plen = state->scope->plen;
 
     /* fixup local references */
     for (i = 0; i < irep->clen; ++i) {
@@ -947,6 +960,8 @@ pic_codegen(pic_state *pic, pic_value obj)
   irep->clen = state->scope->clen;
   irep->irep = pic_realloc(pic, state->scope->irep, sizeof(struct pic_irep *) * state->scope->ilen);
   irep->ilen = state->scope->ilen;
+  irep->pool = pic_realloc(pic, state->scope->pool, sizeof(pic_value) * state->scope->plen);
+  irep->plen = state->scope->plen;
   irep->cv_num = 0;
   irep->cv_tbl = NULL;
 
@@ -1046,9 +1061,7 @@ print_code(pic_state *pic, struct pic_code c)
       printf("OP_PUSHCHAR\t%c\n", c.u.c);
       break;
     case OP_PUSHCONST:
-      printf("OP_PUSHCONST\t");
-      pic_debug(pic, pic->pool[c.u.i]);
-      puts("");
+      printf("OP_PUSHCONST\t%d\n", c.u.i);
       break;
     case OP_GREF:
       printf("OP_GREF\t%i\n", c.u.i);
diff --git a/src/gc.c b/src/gc.c
index 73252a15..fc4937de 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -438,6 +438,9 @@ gc_mark_object(pic_state *pic, struct pic_object *obj)
     for (i = 0; i < irep->ilen; ++i) {
       gc_mark_object(pic, (struct pic_object *)irep->irep[i]);
     }
+    for (i = 0; i < irep->plen; ++i) {
+      gc_mark(pic, irep->pool[i]);
+    }
     break;
   }
   case PIC_TT_NIL:
@@ -501,11 +504,6 @@ gc_mark_phase(pic_state *pic)
     gc_mark(pic, pic->globals[i]);
   }
 
-  /* pool */
-  for (i = 0; i < pic->plen; ++i) {
-    gc_mark(pic, pic->pool[i]);
-  }
-
   /* library table */
   gc_mark(pic, pic->lib_tbl);
 }
@@ -584,6 +582,7 @@ gc_finalize_object(pic_state *pic, struct pic_object *obj)
     pic_free(pic, irep->code);
     pic_free(pic, irep->cv_tbl);
     pic_free(pic, irep->irep);
+    pic_free(pic, irep->pool);
     break;
   }
   case PIC_TT_NIL:
diff --git a/src/state.c b/src/state.c
index 6a0182c1..a7b987e8 100644
--- a/src/state.c
+++ b/src/state.c
@@ -69,11 +69,6 @@ pic_open(int argc, char *argv[], char **envp)
   pic->lib_tbl = pic_nil_value();
   pic->lib = NULL;
 
-  /* pool */
-  pic->pool = (pic_value *)calloc(PIC_POOL_SIZE, sizeof(pic_value));
-  pic->plen = 0;
-  pic->pcapa = PIC_POOL_SIZE;
-
   /* error handling */
   pic->jmp = NULL;
   pic->errmsg = NULL;
@@ -124,11 +119,9 @@ pic_close(pic_state *pic)
   free(pic->cibase);
   free(pic->rescue);
   free(pic->globals);
-  free(pic->pool);
 
   pic->glen = 0;
   pic->rlen = 0;
-  pic->plen = 0;
   pic->arena_idx = 0;
   pic->lib_tbl = pic_undef_value();
 
diff --git a/src/vm.c b/src/vm.c
index e90e4948..74b134d6 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -472,7 +472,18 @@ pic_apply(pic_state *pic, struct pic_proc *proc, pic_value argv)
       NEXT;
     }
     CASE(OP_PUSHCONST) {
-      PUSH(pic->pool[c.u.i]);
+      pic_value self;
+      struct pic_irep *irep;
+
+      self = pic->ci->fp[0];
+      if (! pic_proc_p(self)) {
+        pic_error(pic, "logic flaw");
+      }
+      irep = pic_proc_ptr(self)->u.irep;
+      if (pic_proc_cfunc_p(self)) {
+        pic_error(pic, "logic flaw");
+      }
+      PUSH(irep->pool[c.u.i]);
       NEXT;
     }
     CASE(OP_GREF) {