diff --git a/extlib/benz/include/picrin/private/state.h b/extlib/benz/include/picrin/private/state.h
index 9a83559a..27c9f560 100644
--- a/extlib/benz/include/picrin/private/state.h
+++ b/extlib/benz/include/picrin/private/state.h
@@ -50,7 +50,7 @@ struct pic_state {
 
   struct code *ip;
 
-  struct lib *lib;
+  const char *lib;
 
   pic_value features;
 
diff --git a/extlib/benz/lib.c b/extlib/benz/lib.c
index b65fa3b0..97881cb1 100644
--- a/extlib/benz/lib.c
+++ b/extlib/benz/lib.c
@@ -160,15 +160,10 @@ void
 pic_make_library(pic_state *pic, const char *lib)
 {
   khash_t(ltable) *h = &pic->ltable;
-  const char *old_lib = NULL;
   pic_value name, env, exports;
   int it;
   int ret;
 
-  if (pic->lib) {
-    old_lib = pic_current_library(pic);
-  }
-
   name = pic_cstr_value(pic, lib);
   env = make_library_env(pic, name);
   exports = pic_make_dict(pic);
@@ -181,16 +176,13 @@ pic_make_library(pic_state *pic, const char *lib)
   kh_val(h, it).name = pic_str_ptr(pic, name);
   kh_val(h, it).env = pic_env_ptr(pic, env);
   kh_val(h, it).exports = pic_dict_ptr(pic, exports);
-
-  if (pic->lib) {
-    pic->lib = get_library(pic, old_lib); /* ltable might be rehashed */
-  }
 }
 
 void
 pic_in_library(pic_state *pic, const char *lib)
 {
-  pic->lib = get_library(pic, lib);
+  get_library(pic, lib);
+  pic->lib = lib;
 }
 
 bool
@@ -202,7 +194,7 @@ pic_find_library(pic_state *pic, const char *lib)
 const char *
 pic_current_library(pic_state *pic)
 {
-  return pic_str(pic, pic_obj_value(pic->lib->name));
+  return pic->lib;
 }
 
 pic_value
@@ -216,23 +208,24 @@ pic_import(pic_state *pic, const char *lib)
 {
   pic_value name, realname, uid;
   int it = 0;
-  struct lib *libp;
+  struct lib *our, *their;
 
-  libp = get_library(pic, lib);
+  our = get_library(pic, pic->lib);
+  their = get_library(pic, lib);
 
-  while (pic_dict_next(pic, pic_obj_value(libp->exports), &it, &name, &realname)) {
-    uid = pic_find_identifier(pic, realname, pic_obj_value(libp->env));
+  while (pic_dict_next(pic, pic_obj_value(their->exports), &it, &name, &realname)) {
+    uid = pic_find_identifier(pic, realname, pic_obj_value(their->env));
     if (! pic_weak_has(pic, pic->globals, uid) && ! pic_weak_has(pic, pic->macros, uid)) {
       pic_error(pic, "attempted to export undefined variable", 1, realname);
     }
-    pic_put_identifier(pic, name, uid, pic_obj_value(pic->lib->env));
+    pic_put_identifier(pic, name, uid, pic_obj_value(our->env));
   }
 }
 
 void
 pic_export(pic_state *pic, pic_value name)
 {
-  pic_dict_set(pic, pic_obj_value(pic->lib->exports), name, name);
+  pic_dict_set(pic, pic_obj_value(get_library(pic, pic->lib)->exports), name, name);
 }
 
 static pic_value
@@ -266,7 +259,7 @@ pic_lib_current_library(pic_state *pic)
   n = pic_get_args(pic, "|z", &lib);
 
   if (n == 0) {
-    return pic_obj_value(pic->lib->name);
+    return pic_cstr_value(pic, pic_current_library(pic));
   }
   else {
     pic_in_library(pic, lib);
@@ -302,7 +295,7 @@ pic_lib_library_import(pic_state *pic)
     pic_error(pic, "attempted to export undefined variable", 1, realname);
   }
 
-  pic_put_identifier(pic, alias, uid, pic_obj_value(pic->lib->env));
+  pic_put_identifier(pic, alias, uid, pic_obj_value(get_library(pic, pic->lib)->env));
 
   return pic_undef_value(pic);
 }
@@ -319,7 +312,7 @@ pic_lib_library_export(pic_state *pic)
     alias = name;
   }
 
-  pic_dict_set(pic, pic_obj_value(pic->lib->exports), alias, name);
+  pic_dict_set(pic, pic_obj_value(get_library(pic, pic->lib)->exports), alias, name);
 
   return pic_undef_value(pic);
 }
diff --git a/extlib/benz/state.c b/extlib/benz/state.c
index f35f4f0e..0ce27179 100644
--- a/extlib/benz/state.c
+++ b/extlib/benz/state.c
@@ -7,9 +7,19 @@
 #include "picrin/private/object.h"
 #include "picrin/private/state.h"
 
+static pic_value
+pic_features(pic_state *pic)
+{
+  pic_get_args(pic, "");
+
+  return pic->features;
+}
+
 static void
 pic_init_features(pic_state *pic)
 {
+  pic_defun(pic, "features", pic_features);
+
   pic_add_feature(pic, "picrin");
 
 #if __STDC_IEC_559__
@@ -71,25 +81,17 @@ 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_get_args(pic, "");
-
-  return pic->features;
-}
-
-#define import_builtin_syntax(name) do {                                \
-    pic_value nick, real;                                               \
-    nick = pic_intern_lit(pic, "builtin:" name);                        \
-    real = pic_intern_lit(pic, name);                                   \
-    pic_put_identifier(pic, nick, real, pic_obj_value(pic->lib->env));  \
+#define import_builtin_syntax(name) do {                \
+    pic_value nick, real;                               \
+    nick = pic_intern_lit(pic, "builtin:" name);        \
+    real = pic_intern_lit(pic, name);                   \
+    pic_put_identifier(pic, nick, real, env);           \
   } while (0)
 
-#define declare_vm_procedure(name) do {                                 \
-    pic_value sym;                                                      \
-    sym = pic_intern_lit(pic, name);                                    \
-    pic_put_identifier(pic, sym, sym, pic_obj_value(pic->lib->env));    \
+#define declare_vm_procedure(name) do {         \
+    pic_value sym;                              \
+    sym = pic_intern_lit(pic, name);            \
+    pic_put_identifier(pic, sym, sym, env);     \
   } while (0)
 
 void pic_init_bool(pic_state *);
@@ -119,8 +121,7 @@ static void
 pic_init_core(pic_state *pic)
 {
   size_t ai;
-
-  pic_init_features(pic);
+  pic_value env;
 
   pic_deflibrary(pic, "picrin.base");
 
@@ -128,6 +129,8 @@ pic_init_core(pic_state *pic)
 
 #define DONE pic_leave(pic, ai);
 
+  env = pic_library_environment(pic, pic->lib);
+
   import_builtin_syntax("define");
   import_builtin_syntax("set!");
   import_builtin_syntax("quote");
@@ -179,7 +182,7 @@ pic_init_core(pic_state *pic)
   pic_init_write(pic); DONE;
 #endif
 
-  pic_defun(pic, "features", pic_features);
+  pic_init_features(pic);
 
   pic_load_cstr(pic, &pic_boot[0][0]);
 }