diff --git a/extlib/benz/gc.c b/extlib/benz/gc.c
index bcc9d666..93650e52 100644
--- a/extlib/benz/gc.c
+++ b/extlib/benz/gc.c
@@ -520,7 +520,7 @@ gc_mark_global_symbols(pic_state *pic)
   M(sDEFINE); M(sLAMBDA); M(sIF); M(sBEGIN); M(sQUOTE); M(sSETBANG);
   M(sQUASIQUOTE); M(sUNQUOTE); M(sUNQUOTE_SPLICING);
   M(sDEFINE_SYNTAX); M(sIMPORT); M(sEXPORT);
-  M(sDEFINE_LIBRARY); M(sIN_LIBRARY);
+  M(sDEFINE_LIBRARY);
   M(sCOND_EXPAND); M(sAND); M(sOR); M(sELSE); M(sLIBRARY);
   M(sONLY); M(sRENAME); M(sPREFIX); M(sEXCEPT);
   M(sCONS); M(sCAR); M(sCDR); M(sNILP);
@@ -533,7 +533,7 @@ gc_mark_global_symbols(pic_state *pic)
 
   M(rDEFINE); M(rLAMBDA); M(rIF); M(rBEGIN); M(rQUOTE); M(rSETBANG);
   M(rDEFINE_SYNTAX); M(rIMPORT); M(rEXPORT);
-  M(rDEFINE_LIBRARY); M(rIN_LIBRARY);
+  M(rDEFINE_LIBRARY);
   M(rCOND_EXPAND);
   M(rCONS); M(rCAR); M(rCDR); M(rNILP);
   M(rSYMBOLP); M(rPAIRP);
diff --git a/extlib/benz/include/picrin.h b/extlib/benz/include/picrin.h
index 37b83f42..5b1bd3f3 100644
--- a/extlib/benz/include/picrin.h
+++ b/extlib/benz/include/picrin.h
@@ -99,7 +99,7 @@ typedef struct {
   pic_sym *sDEFINE, *sLAMBDA, *sIF, *sBEGIN, *sQUOTE, *sSETBANG;
   pic_sym *sQUASIQUOTE, *sUNQUOTE, *sUNQUOTE_SPLICING;
   pic_sym *sDEFINE_SYNTAX, *sIMPORT, *sEXPORT;
-  pic_sym *sDEFINE_LIBRARY, *sIN_LIBRARY;
+  pic_sym *sDEFINE_LIBRARY;
   pic_sym *sCOND_EXPAND, *sAND, *sOR, *sELSE, *sLIBRARY;
   pic_sym *sONLY, *sRENAME, *sPREFIX, *sEXCEPT;
   pic_sym *sCONS, *sCAR, *sCDR, *sNILP;
@@ -113,7 +113,7 @@ typedef struct {
 
   pic_sym *rDEFINE, *rLAMBDA, *rIF, *rBEGIN, *rQUOTE, *rSETBANG;
   pic_sym *rDEFINE_SYNTAX, *rIMPORT, *rEXPORT;
-  pic_sym *rDEFINE_LIBRARY, *rIN_LIBRARY;
+  pic_sym *rDEFINE_LIBRARY;
   pic_sym *rCOND_EXPAND;
   pic_sym *rCONS, *rCAR, *rCDR, *rNILP;
   pic_sym *rSYMBOLP, *rPAIRP;
@@ -218,7 +218,6 @@ pic_value pic_eval(pic_state *, pic_value, struct pic_lib *);
 struct pic_proc *pic_compile(pic_state *, pic_value, struct pic_lib *);
 pic_value pic_macroexpand(pic_state *, pic_value, struct pic_lib *);
 
-void pic_in_library(pic_state *, pic_value);
 struct pic_lib *pic_make_library(pic_state *, pic_value);
 struct pic_lib *pic_find_library(pic_state *, pic_value);
 
diff --git a/extlib/benz/lib.c b/extlib/benz/lib.c
index 853b61f1..8e6516ad 100644
--- a/extlib/benz/lib.c
+++ b/extlib/benz/lib.c
@@ -12,7 +12,6 @@ setup_default_env(pic_state *pic, struct pic_env *env)
   pic_define_syntactic_keyword(pic, env, pic->sDEFINE_LIBRARY, pic->rDEFINE_LIBRARY);
   pic_define_syntactic_keyword(pic, env, pic->sIMPORT, pic->rIMPORT);
   pic_define_syntactic_keyword(pic, env, pic->sEXPORT, pic->rEXPORT);
-  pic_define_syntactic_keyword(pic, env, pic->sIN_LIBRARY, pic->rIN_LIBRARY);
   pic_define_syntactic_keyword(pic, env, pic->sCOND_EXPAND, pic->rCOND_EXPAND);
 }
 
@@ -43,18 +42,6 @@ pic_make_library(pic_state *pic, pic_value name)
   return lib;
 }
 
-void
-pic_in_library(pic_state *pic, pic_value spec)
-{
-  struct pic_lib *lib;
-
-  lib = pic_find_library(pic, spec);
-  if (! lib) {
-    pic_errorf(pic, "library not found: ~a", spec);
-  }
-  pic->lib = lib;
-}
-
 struct pic_lib *
 pic_find_library(pic_state *pic, pic_value spec)
 {
@@ -298,45 +285,33 @@ pic_lib_export(pic_state *pic)
 static pic_value
 pic_lib_define_library(pic_state *pic)
 {
-  struct pic_lib *prev = pic->lib;
+  struct pic_lib *lib, *prev = pic->lib;
   size_t argc, i;
   pic_value spec, *argv;
 
   pic_get_args(pic, "o*", &spec, &argc, &argv);
 
-  if (! pic_find_library(pic, spec)) {
-    pic_make_library(pic, spec);
+  if ((lib = pic_find_library(pic, spec)) == NULL) {
+    lib = pic_make_library(pic, spec);
   }
 
   pic_try {
-    pic_in_library(pic, spec);
+    pic->lib = lib;
 
     for (i = 0; i < argc; ++i) {
       pic_void(pic_eval(pic, argv[i], pic->lib));
     }
 
-    pic_in_library(pic, prev->name);
+    pic->lib = prev;
   }
   pic_catch {
-    pic_in_library(pic, prev->name); /* restores pic->lib even if an error occurs */
+    pic->lib = prev;   /* restores pic->lib even if an error occured */
     pic_raise(pic, pic->err);
   }
 
   return pic_undef_value();
 }
 
-static pic_value
-pic_lib_in_library(pic_state *pic)
-{
-  pic_value spec;
-
-  pic_get_args(pic, "o", &spec);
-
-  pic_in_library(pic, spec);
-
-  return pic_undef_value();
-}
-
 void
 pic_init_lib(pic_state *pic)
 {
@@ -346,5 +321,4 @@ pic_init_lib(pic_state *pic)
   pic_defmacro(pic, pic->sIMPORT, pic->rIMPORT, pic_lib_import);
   pic_defmacro(pic, pic->sEXPORT, pic->rEXPORT, pic_lib_export);
   pic_defmacro(pic, pic->sDEFINE_LIBRARY, pic->rDEFINE_LIBRARY, pic_lib_define_library);
-  pic_defmacro(pic, pic->sIN_LIBRARY, pic->rIN_LIBRARY, pic_lib_in_library);
 }
diff --git a/extlib/benz/state.c b/extlib/benz/state.c
index adc7b921..0caa2a6b 100644
--- a/extlib/benz/state.c
+++ b/extlib/benz/state.c
@@ -269,7 +269,6 @@ pic_open(int argc, char *argv[], char **envp, pic_allocf allocf)
   S(sIMPORT, "import");
   S(sEXPORT, "export");
   S(sDEFINE_LIBRARY, "define-library");
-  S(sIN_LIBRARY, "in-library");
   S(sCOND_EXPAND, "cond-expand");
   S(sAND, "and");
   S(sOR, "or");
@@ -321,7 +320,6 @@ pic_open(int argc, char *argv[], char **envp, pic_allocf allocf)
   R(rIMPORT, "import");
   R(rEXPORT, "export");
   R(rDEFINE_LIBRARY, "define-library");
-  R(rIN_LIBRARY, "in-library");
   R(rCOND_EXPAND, "cond-expand");
   R(rCONS, "cons");
   R(rCAR, "car");