diff --git a/contrib/20.r7rs/src/file.c b/contrib/20.r7rs/src/file.c
index 340a5e6d..dd94803c 100644
--- a/contrib/20.r7rs/src/file.c
+++ b/contrib/20.r7rs/src/file.c
@@ -11,7 +11,7 @@ file_error(pic_state *pic, const char *msg)
 {
   struct pic_error *e;
 
-  e = pic_make_error(pic, pic->sFILE, msg, pic_nil_value());
+  e = pic_make_error(pic, pic_intern_cstr(pic, "file"), msg, pic_nil_value());
 
   pic_raise(pic, pic_obj_value(e));
 }
diff --git a/extlib/benz/gc.c b/extlib/benz/gc.c
index d9bda339..d2849dc0 100644
--- a/extlib/benz/gc.c
+++ b/extlib/benz/gc.c
@@ -524,15 +524,12 @@ gc_mark_global_symbols(pic_state *pic)
   M(sQUOTE); M(sQUASIQUOTE); M(sUNQUOTE); M(sUNQUOTE_SPLICING);
   M(sSYNTAX_QUOTE); M(sSYNTAX_QUASIQUOTE); M(sSYNTAX_UNQUOTE); M(sSYNTAX_UNQUOTE_SPLICING);
   M(sDEFINE_LIBRARY); M(sIMPORT); M(sEXPORT); M(sCOND_EXPAND);
-  M(sREAD); M(sFILE);
   M(sCALL); M(sGREF); M(sLREF); M(sCREF);
 
   M(uDEFINE); M(uLAMBDA); M(uIF); M(uBEGIN); M(uQUOTE); M(uSETBANG); M(uDEFINE_MACRO);
   M(uDEFINE_LIBRARY); M(uIMPORT); M(uEXPORT); M(uCOND_EXPAND);
-  M(uCONS); M(uCAR); M(uCDR); M(uNILP);
-  M(uSYMBOLP); M(uPAIRP);
-  M(uADD); M(uSUB); M(uMUL); M(uDIV);
-  M(uEQ); M(uLT); M(uLE); M(uGT); M(uGE); M(uNOT);
+  M(uCONS); M(uCAR); M(uCDR); M(uNILP); M(uSYMBOLP); M(uPAIRP);
+  M(uADD); M(uSUB); M(uMUL); M(uDIV); M(uEQ); M(uLT); M(uLE); M(uGT); M(uGE); M(uNOT);
   M(uVALUES); M(uCALL_WITH_VALUES);
 }
 
diff --git a/extlib/benz/include/picrin.h b/extlib/benz/include/picrin.h
index a52fad61..45b8a22d 100644
--- a/extlib/benz/include/picrin.h
+++ b/extlib/benz/include/picrin.h
@@ -99,7 +99,6 @@ struct pic_state {
   pic_sym *sSYNTAX_QUOTE, *sSYNTAX_QUASIQUOTE, *sSYNTAX_UNQUOTE, *sSYNTAX_UNQUOTE_SPLICING;
   pic_sym *sDEFINE_LIBRARY, *sIMPORT, *sEXPORT, *sCOND_EXPAND;
   pic_sym *sGREF, *sCREF, *sLREF, *sCALL;
-  pic_sym *sREAD, *sFILE;
 
   pic_sym *uDEFINE, *uLAMBDA, *uIF, *uBEGIN, *uQUOTE, *uSETBANG, *uDEFINE_MACRO;
   pic_sym *uDEFINE_LIBRARY, *uIMPORT, *uEXPORT, *uCOND_EXPAND;
diff --git a/extlib/benz/port.c b/extlib/benz/port.c
index bc5ab406..337d0ecd 100644
--- a/extlib/benz/port.c
+++ b/extlib/benz/port.c
@@ -98,6 +98,16 @@ file_open(pic_state *pic, const char *name, const char *mode) {
   }
 }
 
+PIC_NORETURN static void
+file_error(pic_state *pic, const char *msg)
+{
+  struct pic_error *e;
+
+  e = pic_make_error(pic, pic_intern_cstr(pic, "file"), msg, pic_nil_value());
+
+  pic_raise(pic, pic_obj_value(e));
+}
+
 struct pic_port *
 pic_open_file(pic_state *pic, const char *name, int flags) {
   struct pic_port *port;
@@ -108,8 +118,7 @@ pic_open_file(pic_state *pic, const char *name, int flags) {
     mode = 'w';
   }
   if ((file = file_open(pic, name, &mode)) == NULL) {
-    pic_str *msg = pic_format(pic, "could not open file '%s'", name);
-    pic_raise(pic, pic_obj_value(pic_make_error(pic, pic->sFILE, pic_str_cstr(pic, msg), pic_nil_value())));
+    file_error(pic, pic_str_cstr(pic, pic_format(pic, "could not open file '%s'", name)));
   }
 
   port = (struct pic_port *)pic_obj_alloc(pic, sizeof(struct pic_port), PIC_TT_PORT);
diff --git a/extlib/benz/read.c b/extlib/benz/read.c
index c7abf434..537437d0 100644
--- a/extlib/benz/read.c
+++ b/extlib/benz/read.c
@@ -14,7 +14,7 @@ read_error(pic_state *pic, const char *msg)
 {
   struct pic_error *e;
 
-  e = pic_make_error(pic, pic->sREAD, msg, pic_nil_value());
+  e = pic_make_error(pic, pic_intern_cstr(pic, "read"), msg, pic_nil_value());
 
   pic_raise(pic, pic_obj_value(e));
 }
diff --git a/extlib/benz/state.c b/extlib/benz/state.c
index ed2751bf..c06474f1 100644
--- a/extlib/benz/state.c
+++ b/extlib/benz/state.c
@@ -314,8 +314,6 @@ pic_open(pic_allocf allocf, void *userdata)
   S(sEXPORT, "export");
   S(sDEFINE_LIBRARY, "define-library");
   S(sCOND_EXPAND, "cond-expand");
-  S(sREAD, "read");
-  S(sFILE, "file");
   S(sCALL, "call");
   S(sGREF, "gref");
   S(sLREF, "lref");