diff --git a/extlib/benz/codegen.c b/extlib/benz/codegen.c
index 8bac2f3e..a58d24c8 100644
--- a/extlib/benz/codegen.c
+++ b/extlib/benz/codegen.c
@@ -9,6 +9,7 @@
 #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/dict.c b/extlib/benz/dict.c
index bdfc40fd..b9c18cce 100644
--- a/extlib/benz/dict.c
+++ b/extlib/benz/dict.c
@@ -7,6 +7,7 @@
 #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/include/picrin.h b/extlib/benz/include/picrin.h
index 8092fb96..c2a8c6ab 100644
--- a/extlib/benz/include/picrin.h
+++ b/extlib/benz/include/picrin.h
@@ -51,9 +51,6 @@ extern "C" {
 #include "picrin/util.h"
 #include "picrin/value.h"
 
-#define pic_sym(v) pic_ptr(v)
-#define pic_sym_p(v) (pic_type(v) == PIC_TT_SYMBOL)
-
 typedef struct pic_code pic_code;
 
 struct pic_winder {
diff --git a/extlib/benz/include/picrin/symbol.h b/extlib/benz/include/picrin/symbol.h
index 84a706bc..629633e7 100644
--- a/extlib/benz/include/picrin/symbol.h
+++ b/extlib/benz/include/picrin/symbol.h
@@ -14,6 +14,9 @@ struct pic_symbol {
   pic_str *str;
 };
 
+#define pic_sym(v) pic_ptr(v)
+#define pic_sym_p(v) (pic_type(v) == PIC_TT_SYMBOL)
+
 #if defined(__cplusplus)
 }
 #endif
diff --git a/extlib/benz/lib.c b/extlib/benz/lib.c
index a4874156..217ba8d7 100644
--- a/extlib/benz/lib.c
+++ b/extlib/benz/lib.c
@@ -10,6 +10,7 @@
 #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/macro.c b/extlib/benz/macro.c
index ed3f85a0..5286f7d8 100644
--- a/extlib/benz/macro.c
+++ b/extlib/benz/macro.c
@@ -11,6 +11,7 @@
 #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/read.c b/extlib/benz/read.c
index f7637dc1..00e6fe8c 100644
--- a/extlib/benz/read.c
+++ b/extlib/benz/read.c
@@ -11,6 +11,7 @@
 #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/vm.c b/extlib/benz/vm.c
index db54e0ba..7bbaaf24 100644
--- a/extlib/benz/vm.c
+++ b/extlib/benz/vm.c
@@ -15,6 +15,7 @@
 #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 ee521079..ac374fe8 100644
--- a/extlib/benz/write.c
+++ b/extlib/benz/write.c
@@ -11,6 +11,7 @@
 #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)