1 files changed, 5 insertions, 1 deletions
diff --git a/lib/net/imap.rb b/lib/net/imap.rb
index 0f6a4372d5..3404700297 100644
--- a/lib/net/imap.rb
+++ b/lib/net/imap.rb
@@ -311,7 +311,11 @@ module Net
         @receiver_thread.raise(e)
       end
       @receiver_thread.join
-      @sock.close
+      synchronize do
+        unless @sock.closed?
+          @sock.close 
+        end
+      end
       raise e if e
     end