diff --git a/psycopg2cffi/_impl/adapters.py b/psycopg2cffi/_impl/adapters.py
index 108a7da..20e91cf 100644
--- a/psycopg2cffi/_impl/adapters.py
+++ b/psycopg2cffi/_impl/adapters.py
@@ -289,7 +289,10 @@ def _getquoted(param, conn):
     """Helper method"""
     if param is None:
         return b'NULL'
-    adapter = adapt(param)
+    if isinstance(param, _BaseAdapter):
+        adapter = param
+    else:
+        adapter = adapt(param)
     try:
         adapter.prepare(conn)
     except AttributeError: