diff --git a/psycopg/connection_type.c b/psycopg/connection_type.c
index 54633051..4004b420 100644
--- a/psycopg/connection_type.c
+++ b/psycopg/connection_type.c
@@ -547,11 +547,7 @@ psyco_conn_fileno(connectionObject *self)
 
     EXC_IF_CONN_CLOSED(self);
 
-    Py_BEGIN_ALLOW_THREADS;
-    pthread_mutex_lock(&(self->lock));
     socket = (long int)PQsocket(self->pgconn);
-    pthread_mutex_unlock(&(self->lock));
-    Py_END_ALLOW_THREADS;
 
     return PyInt_FromLong(socket);
 }