diff --git a/include/picrin.h b/include/picrin.h
index 3007db00..39b55161 100644
--- a/include/picrin.h
+++ b/include/picrin.h
@@ -144,6 +144,7 @@ void pic_close(pic_state *);
 void pic_add_feature(pic_state *, const char *);
 
 void pic_define(pic_state *, const char *, pic_value); /* automatic export */
+bool pic_defined_p(pic_state *, struct pic_lib *, const char *);
 pic_value pic_ref(pic_state *, struct pic_lib *, const char *);
 void pic_set(pic_state *, struct pic_lib *, const char *, pic_value);
 pic_value pic_funcall(pic_state *pic, const char *name, pic_list args);
diff --git a/vm.c b/vm.c
index f0139de6..ad265e9b 100644
--- a/vm.c
+++ b/vm.c
@@ -425,6 +425,12 @@ pic_define(pic_state *pic, const char *name, pic_value val)
   pic_export(pic, sym);
 }
 
+bool
+pic_defined_p(pic_state *pic, struct pic_lib *lib, const char *name)
+{
+  return pic_find_rename(pic, lib->env, pic_intern_cstr(pic, name), NULL);
+}
+
 pic_value
 pic_ref(pic_state *pic, struct pic_lib *lib, const char *name)
 {