diff --git a/include/picrin/value.h b/include/picrin/value.h
index adc135b4..d155674b 100644
--- a/include/picrin/value.h
+++ b/include/picrin/value.h
@@ -3,6 +3,7 @@
 
 enum pic_vtype {
   PIC_VTYPE_NIL,
+  PIC_VTYPE_INT,
   PIC_VTYPE_HEAP
 };
 
@@ -10,12 +11,14 @@ typedef struct {
   enum pic_vtype type;
   union {
     void *data;
+    int i;
   } u;
 } pic_value;
 
 enum pic_tt {
   /* immediate */
   PIC_TT_NIL,
+  PIC_TT_INT,
   /* heap */
   PIC_TT_PAIR,
   PIC_TT_SYMBOL
@@ -46,6 +49,9 @@ enum pic_tt pic_type(pic_value);
 
 pic_value pic_nil_value();
 pic_value pic_obj_value(void *);
+pic_value pic_int_value(int);
+
+#define pic_int(v) ((v).u.i)
 
 #define pic_nil_p(v) (pic_type(v) == PIC_TT_NIL)
 
diff --git a/src/scan.l b/src/scan.l
index cd8077fe..27416a63 100644
--- a/src/scan.l
+++ b/src/scan.l
@@ -15,7 +15,6 @@ struct parser_control {
 "("	return tLPAREN;
 ")"	return tRPAREN;
 [a-z0-9A-Z]+	{ yylval.datum = pic_intern_cstr(p->pic, yytext); return tSYMBOL; }
-"'"	return tQUOTE;
 
 %%
 
diff --git a/src/value.c b/src/value.c
index 7c6c1604..7c5c6acc 100644
--- a/src/value.c
+++ b/src/value.c
@@ -6,6 +6,8 @@ pic_type(pic_value v)
   switch (v.type) {
   case PIC_VTYPE_NIL:
     return PIC_TT_NIL;
+  case PIC_VTYPE_INT:
+    return PIC_TT_INT;
   case PIC_VTYPE_HEAP:
     return ((struct pic_object *)v.u.data)->tt;
   }
@@ -30,3 +32,13 @@ pic_obj_value(void *ptr)
   v.u.data = ptr;
   return v;
 }
+
+pic_value
+pic_int_value(int i)
+{
+  pic_value v;
+
+  v.type = PIC_VTYPE_INT;
+  v.u.i = i;
+  return v;
+}
diff --git a/src/write.c b/src/write.c
index bc4483e3..c920e455 100644
--- a/src/write.c
+++ b/src/write.c
@@ -20,7 +20,8 @@ pic_debug(pic_state *pic, pic_value obj)
   case PIC_TT_SYMBOL:
     printf("%s", pic_symbol_ptr(obj)->name);
     break;
-  default:
-    abort();
+  case PIC_TT_INT:
+    printf("%d", pic_int(obj));
+    break;
   }
 }