diff --git a/extlib/benz/include/picrin.h b/extlib/benz/include/picrin.h
index b424ac65..ae728792 100644
--- a/extlib/benz/include/picrin.h
+++ b/extlib/benz/include/picrin.h
@@ -180,7 +180,6 @@ pic_sym pic_intern_str(pic_state *, pic_str *);
 pic_sym pic_intern_cstr(pic_state *, const char *);
 const char *pic_symbol_name(pic_state *, pic_sym);
 pic_sym pic_gensym(pic_state *, pic_sym);
-pic_sym pic_ungensym(pic_state *, pic_sym);
 bool pic_interned_p(pic_state *, pic_sym);
 
 pic_value pic_read(pic_state *, struct pic_port *);
diff --git a/extlib/benz/symbol.c b/extlib/benz/symbol.c
index 3fd40f68..c6d68c44 100644
--- a/extlib/benz/symbol.c
+++ b/extlib/benz/symbol.c
@@ -63,22 +63,6 @@ pic_gensym(pic_state *pic, pic_sym base)
   return uniq;
 }
 
-pic_sym
-pic_ungensym(pic_state *pic, pic_sym base)
-{
-  const char *name, *occr;
-
-  if (pic_interned_p(pic, base)) {
-    return base;
-  }
-
-  name = pic_symbol_name(pic, base);
-  if ((occr = strrchr(name, '@')) == NULL) {
-    pic_panic(pic, "logic flaw");
-  }
-  return pic_intern(pic, name, (size_t)(occr - name));
-}
-
 bool
 pic_interned_p(pic_state *pic, pic_sym sym)
 {