diff --git a/include/picrin.h b/include/picrin.h
index 79772d22..d4262b45 100644
--- a/include/picrin.h
+++ b/include/picrin.h
@@ -122,8 +122,8 @@ pic_value pic_apply_argv(pic_state *pic, struct pic_proc *, size_t, ...);
 struct pic_proc *pic_codegen(pic_state *, pic_value);
 pic_value pic_macroexpand(pic_state *, pic_value);
 
-void pic_make_library(pic_state *, pic_value);
-void pic_in_library(pic_state *, pic_value);
+void pic_make_library(pic_state *, const char *);
+void pic_in_library(pic_state *, const char *);
 
 void pic_abort(pic_state *, const char *);
 void pic_raise(pic_state *, pic_value);
diff --git a/src/lib.c b/src/lib.c
index f55199b4..9c136b28 100644
--- a/src/lib.c
+++ b/src/lib.c
@@ -4,26 +4,41 @@
 #include "picrin/macro.h"
 #include "xhash/xhash.h"
 
+static pic_value
+lib_spec(pic_state *pic, const char *name)
+{
+  pic_value vs;
+  int r;
+
+  r = pic_parse_cstr(pic, name, &vs);
+  if (r != 1) {
+    pic_error(pic, "invalid library spec given");
+  }
+  return pic_car(pic, vs);
+}
+
 void
-pic_make_library(pic_state *pic, pic_value name)
+pic_make_library(pic_state *pic, const char *name)
 {
   struct pic_lib *lib;
+  pic_value spec = lib_spec(pic, name);
 
   lib = (struct pic_lib *)pic_obj_alloc(pic, sizeof(struct pic_lib), PIC_TT_LIB);
   lib->senv = pic_minimal_syntactic_env(pic);
   lib->exports = xh_new();
 
-  pic->lib_tbl = pic_acons(pic, name, pic_obj_value(lib), pic->lib_tbl);
+  pic->lib_tbl = pic_acons(pic, spec, pic_obj_value(lib), pic->lib_tbl);
 }
 
 void
-pic_in_library(pic_state *pic, pic_value name)
+pic_in_library(pic_state *pic, const char *name)
 {
-  pic_value v;
+  pic_value v, spec = lib_spec(pic, name);
 
-  v = pic_assoc(pic, name, pic->lib_tbl);
+  v = pic_assoc(pic, spec, pic->lib_tbl);
   if (pic_false_p(v)) {
     pic_error(pic, "library not found");
   }
+
   pic->lib = pic_lib_ptr(pic_cdr(pic, v));
 }
diff --git a/src/state.c b/src/state.c
index 9afa08c1..c322e5e7 100644
--- a/src/state.c
+++ b/src/state.c
@@ -119,8 +119,8 @@ pic_open(int argc, char *argv[], char **envp)
   pic_gc_arena_restore(pic, ai);
 
   /* set library */
-  pic_make_library(pic, pic_symbol_value(pic_intern_cstr(pic, "user")));
-  pic_in_library(pic, pic_symbol_value(pic_intern_cstr(pic, "user")));
+  pic_make_library(pic, "user");
+  pic_in_library(pic, "user");
 
   pic_init_core(pic);