From 4604c25c6055a37e5f25a238d2a089759bd5d98a Mon Sep 17 00:00:00 2001
From: Maximilian Hils <git@maximilianhils.com>
Date: Sat, 12 Mar 2016 23:55:56 +0100
Subject: [PATCH] fix #1025, refs #983

---
 mitmproxy/protocol/tls.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mitmproxy/protocol/tls.py b/mitmproxy/protocol/tls.py
index 6913396d5..f014142b6 100644
--- a/mitmproxy/protocol/tls.py
+++ b/mitmproxy/protocol/tls.py
@@ -562,5 +562,6 @@ class TlsLayer(Layer):
 
         # Some applications don't consider the CN and expect the hostname to be in the SANs.
         # For example, Thunderbird 38 will display a warning if the remote host is only the CN.
-        sans.add(host)
+        if host:
+            sans.add(host)
         return self.config.certstore.get_cert(host, list(sans))