diff --git a/extlib/benz/include/picrin.h b/extlib/benz/include/picrin.h
index 5f0c58f0..d0efcc9b 100644
--- a/extlib/benz/include/picrin.h
+++ b/extlib/benz/include/picrin.h
@@ -264,7 +264,6 @@ int pic_str_hash(pic_state *, struct pic_string *);
 #include "picrin/macro.h"
 #include "picrin/pair.h"
 #include "picrin/port.h"
-#include "picrin/record.h"
 #include "picrin/symbol.h"
 
 void *pic_default_allocf(void *, void *, size_t);
diff --git a/extlib/benz/include/picrin/blob.h b/extlib/benz/include/picrin/blob.h
deleted file mode 100644
index 24ca9e2c..00000000
--- a/extlib/benz/include/picrin/blob.h
+++ /dev/null
@@ -1,16 +0,0 @@
-/**
- * See Copyright Notice in picrin.h
- */
-
-#ifndef PICRIN_BLOB_H
-#define PICRIN_BLOB_H
-
-#if defined(__cplusplus)
-extern "C" {
-#endif
-
-#if defined(__cplusplus)
-}
-#endif
-
-#endif
diff --git a/extlib/benz/include/picrin/object.h b/extlib/benz/include/picrin/object.h
index 63473828..831b2c9b 100644
--- a/extlib/benz/include/picrin/object.h
+++ b/extlib/benz/include/picrin/object.h
@@ -122,6 +122,21 @@ struct pic_proc {
 struct pic_proc *pic_make_proc(pic_state *, pic_func_t, int, pic_value *);
 struct pic_proc *pic_make_proc_irep(pic_state *, struct pic_irep *, struct pic_context *);
 
+
+/* record */
+
+struct pic_record {
+  PIC_OBJECT_HEADER
+  pic_value type;
+  pic_value datum;
+};
+
+#define pic_rec_p(pic, v) (pic_type(pic, v) == PIC_TYPE_RECORD)
+#define pic_rec_ptr(v) ((struct pic_record *)pic_obj_ptr(v))
+
+struct pic_record *pic_make_rec(pic_state *, pic_value, pic_value);
+
+
 #if defined(__cplusplus)
 }
 #endif
diff --git a/extlib/benz/include/picrin/record.h b/extlib/benz/include/picrin/record.h
deleted file mode 100644
index 0549fa90..00000000
--- a/extlib/benz/include/picrin/record.h
+++ /dev/null
@@ -1,30 +0,0 @@
-/**
- * See Copyright Notice in picrin.h
- */
-
-#ifndef PICRIN_RECORD_H
-#define PICRIN_RECORD_H
-
-#if defined(__cplusplus)
-extern "C" {
-#endif
-
-struct pic_record {
-  PIC_OBJECT_HEADER
-  pic_value type;
-  pic_value datum;
-};
-
-#define pic_rec_p(pic, v) (pic_type(pic, v) == PIC_TYPE_RECORD)
-#define pic_rec_ptr(v) ((struct pic_record *)pic_obj_ptr(v))
-
-struct pic_record *pic_make_rec(pic_state *, pic_value, pic_value);
-
-pic_value pic_rec_type(pic_state *, struct pic_record *);
-pic_value pic_rec_datum(pic_state *, struct pic_record *);
-
-#if defined(__cplusplus)
-}
-#endif
-
-#endif
diff --git a/extlib/benz/include/picrin/string.h b/extlib/benz/include/picrin/string.h
deleted file mode 100644
index ac5d2ce8..00000000
--- a/extlib/benz/include/picrin/string.h
+++ /dev/null
@@ -1,16 +0,0 @@
-/**
- * See Copyright Notice in picrin.h
- */
-
-#ifndef PICRIN_STRING_H
-#define PICRIN_STRING_H
-
-#if defined(__cplusplus)
-extern "C" {
-#endif
-
-#if defined(__cplusplus)
-}
-#endif
-
-#endif
diff --git a/extlib/benz/record.c b/extlib/benz/record.c
index c338989a..82d58fd8 100644
--- a/extlib/benz/record.c
+++ b/extlib/benz/record.c
@@ -3,6 +3,7 @@
  */
 
 #include "picrin.h"
+#include "picrin/object.h"
 
 struct pic_record *
 pic_make_rec(pic_state *pic, pic_value type, pic_value datum)
@@ -16,18 +17,6 @@ pic_make_rec(pic_state *pic, pic_value type, pic_value datum)
   return rec;
 }
 
-pic_value
-pic_rec_type(pic_state PIC_UNUSED(*pic), struct pic_record *rec)
-{
-  return rec->type;
-}
-
-pic_value
-pic_rec_datum(pic_state PIC_UNUSED(*pic), struct pic_record *rec)
-{
-  return rec->datum;
-}
-
 static pic_value
 pic_rec_make_record(pic_state *pic)
 {
@@ -55,7 +44,7 @@ pic_rec_record_type(pic_state *pic)
 
   pic_get_args(pic, "r", &rec);
 
-  return pic_rec_type(pic, rec);
+  return rec->type;
 }
 
 static pic_value
@@ -65,7 +54,7 @@ pic_rec_record_datum(pic_state *pic)
 
   pic_get_args(pic, "r", &rec);
 
-  return pic_rec_datum(pic, rec);
+  return rec->datum;
 }
 
 void