diff --git a/extlib/benz/include/picrin.h b/extlib/benz/include/picrin.h
index a2944b44..0a4ea451 100644
--- a/extlib/benz/include/picrin.h
+++ b/extlib/benz/include/picrin.h
@@ -272,7 +272,6 @@ int pic_str_hash(pic_state *, struct pic_string *);
 
 #include "picrin/cont.h"
 #include "picrin/macro.h"
-#include "picrin/port.h"
 
 void *pic_default_allocf(void *, void *, size_t);
 
@@ -283,6 +282,9 @@ void *pic_default_allocf(void *, void *, size_t);
 
 struct pic_object *pic_obj_alloc(pic_state *, size_t, int type);
 
+struct pic_port *pic_make_port(pic_state *, xFILE *file);
+void pic_close_port(pic_state *, struct pic_port *port);
+
 #define pic_void(exec)                          \
   pic_void_(PIC_GENSYM(ai), exec)
 #define pic_void_(ai,exec) do {                 \
diff --git a/extlib/benz/include/picrin/object.h b/extlib/benz/include/picrin/object.h
index b5d0c8b4..a15b1def 100644
--- a/extlib/benz/include/picrin/object.h
+++ b/extlib/benz/include/picrin/object.h
@@ -190,6 +190,16 @@ struct pic_error {
 struct pic_error *pic_make_error(pic_state *, const char *, const char *, pic_value);
 
 
+/* port */
+
+struct pic_port {
+  PIC_OBJECT_HEADER
+  xFILE *file;
+};
+
+#define pic_port_ptr(v) ((struct pic_port *)pic_obj_ptr(v))
+
+
 #if defined(__cplusplus)
 }
 #endif
diff --git a/extlib/benz/include/picrin/port.h b/extlib/benz/include/picrin/port.h
deleted file mode 100644
index 95ddc487..00000000
--- a/extlib/benz/include/picrin/port.h
+++ /dev/null
@@ -1,26 +0,0 @@
-/**
- * See Copyright Notice in picrin.h
- */
-
-#ifndef PICRIN_PORT_H
-#define PICRIN_PORT_H
-
-#if defined(__cplusplus)
-extern "C" {
-#endif
-
-struct pic_port {
-  PIC_OBJECT_HEADER
-  xFILE *file;
-};
-
-#define pic_port_ptr(v) ((struct pic_port *)pic_obj_ptr(v))
-
-struct pic_port *pic_make_port(pic_state *, xFILE *file);
-void pic_close_port(pic_state *, struct pic_port *port);
-
-#if defined(__cplusplus)
-}
-#endif
-
-#endif