diff --git a/Makefile b/Makefile
index 925f7479..61c5bd60 100644
--- a/Makefile
+++ b/Makefile
@@ -21,6 +21,7 @@ LIBPICRIN_SRCS = \
 	lib/weak.c\
 	lib/ext/boot.c\
 	lib/ext/lib.c\
+	lib/ext/file.c\
 	lib/ext/load.c\
 	lib/ext/read.c\
 	lib/ext/write.c
diff --git a/lib/ext/file.c b/lib/ext/file.c
new file mode 100644
index 00000000..02b07a55
--- /dev/null
+++ b/lib/ext/file.c
@@ -0,0 +1,87 @@
+/**
+ * See Copyright Notice in picrin.h
+ */
+
+#include <stdio.h>
+
+#include "picrin.h"
+
+#if PIC_USE_LIBC
+
+static int
+file_read(pic_state *PIC_UNUSED(pic), void *cookie, char *ptr, int size) {
+  FILE *file = cookie;
+  int r;
+
+  size = 1;                     /* override size */
+
+  r = (int)fread(ptr, 1, (size_t)size, file);
+  if (r < size && ferror(file)) {
+    return -1;
+  }
+  if (r == 0 && feof(file)) {
+    clearerr(file);
+  }
+  return r;
+}
+
+static int
+file_write(pic_state *PIC_UNUSED(pic), void *cookie, const char *ptr, int size) {
+  FILE *file = cookie;
+  int r;
+
+  r = (int)fwrite(ptr, 1, (size_t)size, file);
+  if (r < size) {
+    return -1;
+  }
+  fflush(cookie);
+  return r;
+}
+
+static long
+file_seek(pic_state *PIC_UNUSED(pic), void *cookie, long pos, int whence) {
+  switch (whence) {
+  case PIC_SEEK_CUR:
+    whence = SEEK_CUR;
+    break;
+  case PIC_SEEK_SET:
+    whence = SEEK_SET;
+    break;
+  case PIC_SEEK_END:
+    whence = SEEK_END;
+    break;
+  }
+  if (fseek(cookie, pos, whence) == 0) {
+    return ftell(cookie);
+  }
+  return -1;
+}
+
+static int
+file_close(pic_state *PIC_UNUSED(pic), void *cookie) {
+  return fclose(cookie);
+}
+
+pic_value
+pic_fopen(pic_state *pic, FILE *fp, const char *mode) {
+  static const pic_port_type file_rd = { file_read, 0, file_seek, file_close };
+  static const pic_port_type file_wr = { 0, file_write, file_seek, file_close };
+
+  if (*mode == 'r') {
+    return pic_funopen(pic, fp, &file_rd);
+  } else {
+    return pic_funopen(pic, fp, &file_wr);
+  }
+}
+
+void
+pic_init_file(pic_state *PIC_UNUSED(pic))
+{
+#if PIC_USE_STDIO
+  pic_defvar(pic, "current-input-port", pic_fopen(pic, stdin, "r"));
+  pic_defvar(pic, "current-output-port", pic_fopen(pic, stdout, "w"));
+  pic_defvar(pic, "current-error-port", pic_fopen(pic, stdout, "w"));
+#endif
+}
+
+#endif
diff --git a/lib/port.c b/lib/port.c
index 2550cb77..0a7a84f3 100644
--- a/lib/port.c
+++ b/lib/port.c
@@ -10,15 +10,6 @@
 # define EOF (-1)
 #endif
 
-bool
-pic_port_p(pic_state *pic, pic_value obj, const pic_port_type *type)
-{
-  if (pic_type(pic, obj) != PIC_TYPE_PORT) {
-    return false;
-  }
-  return type == NULL || port_ptr(pic, obj)->file.vtable == type;
-}
-
 pic_value
 pic_funopen(pic_state *pic, void *cookie, const pic_port_type *type)
 {
@@ -316,80 +307,6 @@ pic_fseek(pic_state *pic, pic_value port, long offset, int whence)
   return 0;
 }
 
-#if PIC_USE_STDIO
-
-static int
-file_read(pic_state *PIC_UNUSED(pic), void *cookie, char *ptr, int size) {
-  FILE *file = cookie;
-  int r;
-
-  size = 1;                     /* override size */
-
-  r = (int)fread(ptr, 1, (size_t)size, file);
-  if (r < size && ferror(file)) {
-    return -1;
-  }
-  if (r == 0 && feof(file)) {
-    clearerr(file);
-  }
-  return r;
-}
-
-static int
-file_write(pic_state *PIC_UNUSED(pic), void *cookie, const char *ptr, int size) {
-  FILE *file = cookie;
-  int r;
-
-  r = (int)fwrite(ptr, 1, (size_t)size, file);
-  if (r < size) {
-    return -1;
-  }
-  fflush(cookie);
-  return r;
-}
-
-static long
-file_seek(pic_state *PIC_UNUSED(pic), void *cookie, long pos, int whence) {
-  switch (whence) {
-  case PIC_SEEK_CUR:
-    whence = SEEK_CUR;
-    break;
-  case PIC_SEEK_SET:
-    whence = SEEK_SET;
-    break;
-  case PIC_SEEK_END:
-    whence = SEEK_END;
-    break;
-  }
-  if (fseek(cookie, pos, whence) == 0) {
-    return ftell(cookie);
-  }
-  return -1;
-}
-
-static int
-file_close(pic_state *PIC_UNUSED(pic), void *cookie) {
-  return fclose(cookie);
-}
-
-static const pic_port_type file_rd = {
-  file_read, 0, file_seek, file_close
-};
-static const pic_port_type file_wr = {
-  0, file_write, file_seek, file_close
-};
-
-pic_value
-pic_fopen(pic_state *pic, FILE *fp, const char *mode) {
-  if (*mode == 'r') {
-    return pic_funopen(pic, fp, &file_rd);
-  } else {
-    return pic_funopen(pic, fp, &file_wr);
-  }
-}
-
-#endif
-
 typedef struct { char *buf; long pos, end, capa; } xbuf_t;
 
 static int
@@ -450,16 +367,11 @@ string_close(pic_state *pic, void *cookie)
   return 0;
 }
 
-static const pic_port_type string_rd = {
-  string_read, 0, string_seek, string_close
-};
-static const pic_port_type string_wr = {
-  0, string_write, string_seek, string_close
-};
-
 pic_value
 pic_fmemopen(pic_state *pic, const char *data, int size, const char *mode)
 {
+  static const pic_port_type string_rd = { string_read, 0, string_seek, string_close };
+  static const pic_port_type string_wr = { 0, string_write, string_seek, string_close };
   xbuf_t *m;
 
   m = pic_malloc(pic, sizeof(xbuf_t));
@@ -493,6 +405,15 @@ pic_fgetbuf(pic_state *pic, pic_value port, const char **buf, int *len)
   return 0;
 }
 
+bool
+pic_port_p(pic_state *pic, pic_value obj, const pic_port_type *type)
+{
+  if (pic_type(pic, obj) != PIC_TYPE_PORT) {
+    return false;
+  }
+  return type == NULL || port_ptr(pic, obj)->file.vtable == type;
+}
+
 static pic_value
 pic_port_input_port_p(pic_state *pic)
 {
@@ -746,12 +667,6 @@ pic_port_flush(pic_state *pic)
 void
 pic_init_port(pic_state *pic)
 {
-#if PIC_USE_STDIO
-  pic_defvar(pic, "current-input-port", pic_fopen(pic, stdin, "r"));
-  pic_defvar(pic, "current-output-port", pic_fopen(pic, stdout, "w"));
-  pic_defvar(pic, "current-error-port", pic_fopen(pic, stdout, "w"));
-#endif
-
   pic_defun(pic, "port?", pic_port_port_p);
   pic_defun(pic, "input-port?", pic_port_input_port_p);
   pic_defun(pic, "output-port?", pic_port_output_port_p);
diff --git a/lib/state.c b/lib/state.c
index 94da5cc5..3c9295b3 100644
--- a/lib/state.c
+++ b/lib/state.c
@@ -7,18 +7,33 @@
 #include "object.h"
 #include "state.h"
 
+void
+pic_add_feature(pic_state *pic, const char *feature)
+{
+  pic_push(pic, pic_intern_cstr(pic, feature), pic->features);
+}
+
 static pic_value
-pic_features(pic_state *pic)
+pic_state_features(pic_state *pic)
 {
   pic_get_args(pic, "");
 
   return pic->features;
 }
 
-static void
-pic_init_features(pic_state *pic)
+static pic_value
+pic_state_global_objects(pic_state *pic)
 {
-  pic_defun(pic, "features", pic_features);
+  pic_get_args(pic, "");
+
+  return pic->globals;
+}
+
+static void
+pic_init_state(pic_state *pic)
+{
+  pic_defun(pic, "features", pic_state_features);
+  pic_defun(pic, "global-objects", pic_state_global_objects);
 
   pic_add_feature(pic, "picrin");
 
@@ -75,20 +90,6 @@ pic_init_features(pic_state *pic)
 #endif
 }
 
-void
-pic_add_feature(pic_state *pic, const char *feature)
-{
-  pic_push(pic, pic_intern_cstr(pic, feature), pic->features);
-}
-
-static pic_value
-pic_global_objects(pic_state *pic)
-{
-  pic_get_args(pic, "");
-
-  return pic->globals;
-}
-
 void pic_init_bool(pic_state *);
 void pic_init_pair(pic_state *);
 void pic_init_port(pic_state *);
@@ -108,6 +109,8 @@ void pic_init_dict(pic_state *);
 void pic_init_record(pic_state *);
 void pic_init_weak(pic_state *);
 void pic_init_load(pic_state *);
+void pic_init_file(pic_state *);
+void pic_init_state(pic_state *);
 
 void pic_boot(pic_state *);
 
@@ -118,9 +121,6 @@ pic_init_core(pic_state *pic)
 {
   size_t ai = pic_enter(pic);
 
-  pic_defun(pic, "global-objects", pic_global_objects);
-
-  pic_init_features(pic); DONE;
   pic_init_bool(pic); DONE;
   pic_init_pair(pic); DONE;
   pic_init_port(pic); DONE;
@@ -134,15 +134,19 @@ pic_init_core(pic_state *pic)
   pic_init_error(pic); DONE;
   pic_init_str(pic); DONE;
   pic_init_var(pic); DONE;
-  pic_init_read(pic); DONE;
   pic_init_dict(pic); DONE;
   pic_init_record(pic); DONE;
   pic_init_weak(pic); DONE;
+  pic_init_state(pic); DONE;
   pic_init_load(pic); DONE;
+  pic_init_read(pic); DONE;
 
 #if PIC_USE_WRITE
   pic_init_write(pic); DONE;
 #endif
+#if PIC_USE_LIBC
+  pic_init_file(pic); DONE;
+#endif
 
   pic_boot(pic); DONE;
 }