diff --git a/tryton/pysocket.py b/tryton/pysocket.py
index 428e4ba02e..cfc3df405a 100644
--- a/tryton/pysocket.py
+++ b/tryton/pysocket.py
@@ -50,7 +50,7 @@ class PySocket:
         self.connected = False
         self.buffer = ''
         self.fingerprints = fingerprints
-        if os.path.isfile(ca_certs):
+        if ca_certs and os.path.isfile(ca_certs):
             self.ca_certs = ca_certs
         else:
             self.ca_certs = None