diff --git a/contrib/03.callcc/callcc.c b/contrib/03.callcc/callcc.c
index 09746077..e6750347 100644
--- a/contrib/03.callcc/callcc.c
+++ b/contrib/03.callcc/callcc.c
@@ -1,8 +1,4 @@
 #include "picrin.h"
-#include "picrin/data.h"
-#include "picrin/proc.h"
-#include "picrin/pair.h"
-#include "picrin/cont.h"
 
 struct pic_cont {
   jmp_buf jmp;
diff --git a/contrib/03.file/src/file.c b/contrib/03.file/src/file.c
index 8efd2a77..f0410f9d 100644
--- a/contrib/03.file/src/file.c
+++ b/contrib/03.file/src/file.c
@@ -3,8 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/port.h"
-#include "picrin/error.h"
 
 PIC_NORETURN static void
 file_error(pic_state *pic, const char *msg)
diff --git a/contrib/03.load/src/load.c b/contrib/03.load/src/load.c
index 93f832c6..5efb71c7 100644
--- a/contrib/03.load/src/load.c
+++ b/contrib/03.load/src/load.c
@@ -3,9 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/pair.h"
-#include "picrin/port.h"
-#include "picrin/error.h"
 
 void
 pic_load(pic_state *pic, const char *filename)
diff --git a/contrib/03.mutable-string/mutable-string.c b/contrib/03.mutable-string/mutable-string.c
index 43679a29..6937b0f6 100644
--- a/contrib/03.mutable-string/mutable-string.c
+++ b/contrib/03.mutable-string/mutable-string.c
@@ -1,5 +1,4 @@
 #include "picrin.h"
-#include "picrin/string.h"
 
 void
 pic_str_set(pic_state *pic, pic_str *str, size_t i, char c)
diff --git a/contrib/03.system/src/system.c b/contrib/03.system/src/system.c
index 5ead4d9c..3265d876 100644
--- a/contrib/03.system/src/system.c
+++ b/contrib/03.system/src/system.c
@@ -5,9 +5,6 @@
 #include <stdlib.h>
 
 #include "picrin.h"
-#include "picrin/string.h"
-#include "picrin/pair.h"
-#include "picrin/cont.h"
 
 static pic_value
 pic_system_cmdline(pic_state *pic)
diff --git a/contrib/10.readline/src/readline.c b/contrib/10.readline/src/readline.c
index b516cb6c..fe831ddd 100644
--- a/contrib/10.readline/src/readline.c
+++ b/contrib/10.readline/src/readline.c
@@ -6,9 +6,6 @@
 forget to use the C++ extern "C" to get it to compile.
 */
 #include "picrin.h"
-#include "picrin/pair.h"
-#include "picrin/string.h"
-#include "picrin/port.h"
 
 #if PIC_READLINE_INCLUDE_DIR_SUFFIX == readline
 #include <readline/readline.h>
diff --git a/contrib/10.regexp/src/regexp.c b/contrib/10.regexp/src/regexp.c
index 3a358fab..ce54d65e 100644
--- a/contrib/10.regexp/src/regexp.c
+++ b/contrib/10.regexp/src/regexp.c
@@ -1,8 +1,4 @@
 #include "picrin.h"
-#include "picrin/data.h"
-#include "picrin/pair.h"
-#include "picrin/string.h"
-#include "picrin/cont.h"
 
 #include <regex.h>
 
diff --git a/docs/capi.rst b/docs/capi.rst
index c4464114..a2c31320 100644
--- a/docs/capi.rst
+++ b/docs/capi.rst
@@ -51,7 +51,6 @@ When you use dynamic memory allocation inside C APIs, you must be caseful about
   /** foo.c **/
   #include <stdlib.h>
   #include "picrin.h"
-  #include "picrin/data.h"
 
   /*
    * C-side API
diff --git a/etc/mkloader.pl b/etc/mkloader.pl
index 984f4709..3f5bcb41 100755
--- a/etc/mkloader.pl
+++ b/etc/mkloader.pl
@@ -12,7 +12,6 @@ print <<EOL;
  */
 
 #include "picrin.h"
-#include "picrin/error.h"
 
 EOL
 
diff --git a/extlib/benz/attr.c b/extlib/benz/attr.c
index 169f1e8b..050eaee6 100644
--- a/extlib/benz/attr.c
+++ b/extlib/benz/attr.c
@@ -1,5 +1,4 @@
 #include "picrin.h"
-#include "picrin/dict.h"
 
 struct pic_dict *
 pic_attr(pic_state *pic, pic_value obj)
diff --git a/extlib/benz/blob.c b/extlib/benz/blob.c
index 0169c970..59791ee9 100644
--- a/extlib/benz/blob.c
+++ b/extlib/benz/blob.c
@@ -3,8 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/blob.h"
-#include "picrin/pair.h"
 
 struct pic_blob *
 pic_make_blob(pic_state *pic, size_t len)
diff --git a/extlib/benz/bool.c b/extlib/benz/bool.c
index b81c2155..b5edfe98 100644
--- a/extlib/benz/bool.c
+++ b/extlib/benz/bool.c
@@ -3,10 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/pair.h"
-#include "picrin/vector.h"
-#include "picrin/blob.h"
-#include "picrin/string.h"
 
 static bool
 str_equal_p(pic_state *pic, struct pic_string *str1, struct pic_string *str2)
diff --git a/extlib/benz/codegen.c b/extlib/benz/codegen.c
index bd9fe03b..d998eda9 100644
--- a/extlib/benz/codegen.c
+++ b/extlib/benz/codegen.c
@@ -3,13 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/pair.h"
-#include "picrin/irep.h"
-#include "picrin/proc.h"
-#include "picrin/lib.h"
-#include "picrin/macro.h"
-#include "picrin/dict.h"
-#include "picrin/symbol.h"
 
 #if PIC_NONE_IS_FALSE
 # define OP_PUSHNONE OP_PUSHFALSE
diff --git a/extlib/benz/cont.c b/extlib/benz/cont.c
index 00209c0c..90cccc60 100644
--- a/extlib/benz/cont.c
+++ b/extlib/benz/cont.c
@@ -3,11 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/proc.h"
-#include "picrin/cont.h"
-#include "picrin/pair.h"
-#include "picrin/data.h"
-#include "picrin/error.h"
 
 void
 pic_wind(pic_state *pic, struct pic_winder *here, struct pic_winder *there)
diff --git a/extlib/benz/data.c b/extlib/benz/data.c
index 5d586c56..00042286 100644
--- a/extlib/benz/data.c
+++ b/extlib/benz/data.c
@@ -1,5 +1,4 @@
 #include "picrin.h"
-#include "picrin/data.h"
 
 struct pic_data *
 pic_data_alloc(pic_state *pic, const pic_data_type *type, void *userdata)
diff --git a/extlib/benz/debug.c b/extlib/benz/debug.c
index 65b8e548..2525a656 100644
--- a/extlib/benz/debug.c
+++ b/extlib/benz/debug.c
@@ -3,9 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/string.h"
-#include "picrin/error.h"
-#include "picrin/proc.h"
 
 pic_str *
 pic_get_backtrace(pic_state *pic)
diff --git a/extlib/benz/dict.c b/extlib/benz/dict.c
index 3904dbd0..b802fe06 100644
--- a/extlib/benz/dict.c
+++ b/extlib/benz/dict.c
@@ -3,11 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/dict.h"
-#include "picrin/cont.h"
-#include "picrin/pair.h"
-#include "picrin/error.h"
-#include "picrin/symbol.h"
 
 struct pic_dict *
 pic_make_dict(pic_state *pic)
diff --git a/extlib/benz/error.c b/extlib/benz/error.c
index 2c70e188..d9ea00dd 100644
--- a/extlib/benz/error.c
+++ b/extlib/benz/error.c
@@ -3,13 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/pair.h"
-#include "picrin/proc.h"
-#include "picrin/cont.h"
-#include "picrin/data.h"
-#include "picrin/string.h"
-#include "picrin/error.h"
-#include "picrin/port.h"
 
 void
 pic_panic(pic_state PIC_UNUSED(*pic), const char *msg)
diff --git a/extlib/benz/eval.c b/extlib/benz/eval.c
index d8712760..1006df50 100644
--- a/extlib/benz/eval.c
+++ b/extlib/benz/eval.c
@@ -3,7 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/macro.h"
 
 pic_value
 pic_eval(pic_state *pic, pic_value program, struct pic_lib *lib)
diff --git a/extlib/benz/gc.c b/extlib/benz/gc.c
index 4220c758..9a3c4c25 100644
--- a/extlib/benz/gc.c
+++ b/extlib/benz/gc.c
@@ -3,23 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/gc.h"
-#include "picrin/pair.h"
-#include "picrin/string.h"
-#include "picrin/vector.h"
-#include "picrin/irep.h"
-#include "picrin/proc.h"
-#include "picrin/port.h"
-#include "picrin/blob.h"
-#include "picrin/cont.h"
-#include "picrin/error.h"
-#include "picrin/macro.h"
-#include "picrin/lib.h"
-#include "picrin/data.h"
-#include "picrin/dict.h"
-#include "picrin/record.h"
-#include "picrin/read.h"
-#include "picrin/symbol.h"
 
 union header {
   struct {
diff --git a/extlib/benz/include/picrin.h b/extlib/benz/include/picrin.h
index aca199a0..941935f9 100644
--- a/extlib/benz/include/picrin.h
+++ b/extlib/benz/include/picrin.h
@@ -246,11 +246,29 @@ pic_value pic_display(pic_state *, pic_value);
 pic_value pic_fdisplay(pic_state *, pic_value, xFILE *);
 
 #if DEBUG
-# include "picrin/port.h"
 # define pic_debug(pic,obj) pic_fwrite(pic,obj,pic->xSTDERR->file)
 # define pic_fdebug(pic,obj,file) pic_fwrite(pic,obj,file)
 #endif
 
+#include "picrin/blob.h"
+#include "picrin/cont.h"
+#include "picrin/data.h"
+#include "picrin/dict.h"
+#include "picrin/error.h"
+#include "picrin/gc.h"
+#include "picrin/irep.h"
+#include "picrin/lib.h"
+#include "picrin/macro.h"
+#include "picrin/pair.h"
+#include "picrin/port.h"
+#include "picrin/proc.h"
+#include "picrin/read.h"
+#include "picrin/record.h"
+#include "picrin/string.h"
+#include "picrin/symbol.h"
+#include "picrin/read.h"
+#include "picrin/vector.h"
+
 #if defined(__cplusplus)
 }
 #endif
diff --git a/extlib/benz/include/picrin/error.h b/extlib/benz/include/picrin/error.h
index efb12130..ddf14e85 100644
--- a/extlib/benz/include/picrin/error.h
+++ b/extlib/benz/include/picrin/error.h
@@ -9,8 +9,6 @@
 extern "C" {
 #endif
 
-#include "picrin/cont.h"
-
 struct pic_error {
   PIC_OBJECT_HEADER
   pic_sym *type;
diff --git a/extlib/benz/lib.c b/extlib/benz/lib.c
index 30362ef2..5e364af0 100644
--- a/extlib/benz/lib.c
+++ b/extlib/benz/lib.c
@@ -3,14 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/lib.h"
-#include "picrin/pair.h"
-#include "picrin/macro.h"
-#include "picrin/error.h"
-#include "picrin/string.h"
-#include "picrin/proc.h"
-#include "picrin/dict.h"
-#include "picrin/symbol.h"
 
 struct pic_lib *
 pic_open_library(pic_state *pic, pic_value name)
diff --git a/extlib/benz/load.c b/extlib/benz/load.c
index a6f2eb8d..53220101 100644
--- a/extlib/benz/load.c
+++ b/extlib/benz/load.c
@@ -3,8 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/port.h"
-#include "picrin/error.h"
 
 void
 pic_load_port(pic_state *pic, struct pic_port *port)
diff --git a/extlib/benz/macro.c b/extlib/benz/macro.c
index f934cdd3..219c225d 100644
--- a/extlib/benz/macro.c
+++ b/extlib/benz/macro.c
@@ -3,15 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/pair.h"
-#include "picrin/string.h"
-#include "picrin/proc.h"
-#include "picrin/macro.h"
-#include "picrin/lib.h"
-#include "picrin/error.h"
-#include "picrin/dict.h"
-#include "picrin/cont.h"
-#include "picrin/symbol.h"
 
 pic_sym *
 pic_add_rename(pic_state *pic, struct pic_senv *senv, pic_sym *sym)
diff --git a/extlib/benz/number.c b/extlib/benz/number.c
index 928ba50e..1f02ca0c 100644
--- a/extlib/benz/number.c
+++ b/extlib/benz/number.c
@@ -3,9 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/string.h"
-#include "picrin/cont.h"
-#include "picrin/port.h"
 
 #if ! PIC_ENABLE_FLOAT
 static pic_value
diff --git a/extlib/benz/pair.c b/extlib/benz/pair.c
index 36400af2..17da2394 100644
--- a/extlib/benz/pair.c
+++ b/extlib/benz/pair.c
@@ -3,7 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/pair.h"
 
 pic_value
 pic_cons(pic_state *pic, pic_value car, pic_value cdr)
diff --git a/extlib/benz/port.c b/extlib/benz/port.c
index 20879173..58bd0826 100644
--- a/extlib/benz/port.c
+++ b/extlib/benz/port.c
@@ -3,11 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/proc.h"
-#include "picrin/port.h"
-#include "picrin/string.h"
-#include "picrin/blob.h"
-#include "picrin/error.h"
 
 pic_value
 pic_eof_object()
diff --git a/extlib/benz/proc.c b/extlib/benz/proc.c
index b1a9a795..2f7d2d11 100644
--- a/extlib/benz/proc.c
+++ b/extlib/benz/proc.c
@@ -3,9 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/pair.h"
-#include "picrin/proc.h"
-#include "picrin/irep.h"
 
 struct pic_proc *
 pic_make_proc(pic_state *pic, pic_func_t func, const char *name)
diff --git a/extlib/benz/read.c b/extlib/benz/read.c
index ce60a995..c8cf6d70 100644
--- a/extlib/benz/read.c
+++ b/extlib/benz/read.c
@@ -3,15 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/read.h"
-#include "picrin/error.h"
-#include "picrin/pair.h"
-#include "picrin/string.h"
-#include "picrin/vector.h"
-#include "picrin/blob.h"
-#include "picrin/port.h"
-#include "picrin/proc.h"
-#include "picrin/symbol.h"
 
 static pic_value read(pic_state *pic, struct pic_port *port, int c);
 static pic_value read_nullable(pic_state *pic, struct pic_port *port, int c);
diff --git a/extlib/benz/record.c b/extlib/benz/record.c
index 2a6e85cc..dc35e223 100644
--- a/extlib/benz/record.c
+++ b/extlib/benz/record.c
@@ -3,8 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/record.h"
-#include "picrin/dict.h"
 
 struct pic_record *
 pic_make_record(pic_state *pic, pic_value rectype)
diff --git a/extlib/benz/state.c b/extlib/benz/state.c
index 571c5155..c4207987 100644
--- a/extlib/benz/state.c
+++ b/extlib/benz/state.c
@@ -3,16 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/gc.h"
-#include "picrin/read.h"
-#include "picrin/proc.h"
-#include "picrin/macro.h"
-#include "picrin/cont.h"
-#include "picrin/port.h"
-#include "picrin/error.h"
-#include "picrin/dict.h"
-#include "picrin/pair.h"
-#include "picrin/lib.h"
 
 void
 pic_add_feature(pic_state *pic, const char *feature)
diff --git a/extlib/benz/string.c b/extlib/benz/string.c
index 95a32210..ee1f3527 100644
--- a/extlib/benz/string.c
+++ b/extlib/benz/string.c
@@ -3,10 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/string.h"
-#include "picrin/pair.h"
-#include "picrin/port.h"
-#include "picrin/error.h"
 
 struct pic_chunk {
   char *str;
diff --git a/extlib/benz/symbol.c b/extlib/benz/symbol.c
index 219ee25a..008c52b2 100644
--- a/extlib/benz/symbol.c
+++ b/extlib/benz/symbol.c
@@ -3,8 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/symbol.h"
-#include "picrin/string.h"
 
 pic_sym *
 pic_make_symbol(pic_state *pic, pic_str *str)
diff --git a/extlib/benz/var.c b/extlib/benz/var.c
index 7eb4e08a..e1b7ff06 100644
--- a/extlib/benz/var.c
+++ b/extlib/benz/var.c
@@ -3,8 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/pair.h"
-#include "picrin/proc.h"
 
 static pic_value
 var_lookup(pic_state *pic, pic_value var)
diff --git a/extlib/benz/vector.c b/extlib/benz/vector.c
index 46b02616..08d2f72a 100644
--- a/extlib/benz/vector.c
+++ b/extlib/benz/vector.c
@@ -3,9 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/vector.h"
-#include "picrin/string.h"
-#include "picrin/pair.h"
 
 struct pic_vector *
 pic_make_vec(pic_state *pic, size_t len)
diff --git a/extlib/benz/vm.c b/extlib/benz/vm.c
index fa07c6d2..c6cb42b1 100644
--- a/extlib/benz/vm.c
+++ b/extlib/benz/vm.c
@@ -3,19 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/pair.h"
-#include "picrin/string.h"
-#include "picrin/vector.h"
-#include "picrin/proc.h"
-#include "picrin/port.h"
-#include "picrin/irep.h"
-#include "picrin/blob.h"
-#include "picrin/lib.h"
-#include "picrin/macro.h"
-#include "picrin/error.h"
-#include "picrin/dict.h"
-#include "picrin/record.h"
-#include "picrin/symbol.h"
 
 #define GET_OPERAND(pic,n) ((pic)->ci->fp[(n)])
 
diff --git a/extlib/benz/write.c b/extlib/benz/write.c
index c9e36553..d2c2a807 100644
--- a/extlib/benz/write.c
+++ b/extlib/benz/write.c
@@ -3,15 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/port.h"
-#include "picrin/pair.h"
-#include "picrin/string.h"
-#include "picrin/vector.h"
-#include "picrin/blob.h"
-#include "picrin/dict.h"
-#include "picrin/record.h"
-#include "picrin/proc.h"
-#include "picrin/symbol.h"
 
 static bool
 is_tagged(pic_state *pic, pic_sym *tag, pic_value pair)
diff --git a/src/main.c b/src/main.c
index 5c70fd7f..fbdae10c 100644
--- a/src/main.c
+++ b/src/main.c
@@ -3,8 +3,6 @@
  */
 
 #include "picrin.h"
-#include "picrin/pair.h"
-#include "picrin/error.h"
 
 void pic_init_contrib(pic_state *);
 void pic_load_piclib(pic_state *);