diff --git a/apns2/client.py b/apns2/client.py
index be47fed..e8f012e 100644
--- a/apns2/client.py
+++ b/apns2/client.py
@@ -33,7 +33,7 @@ class APNsClient(object):
 
     def __init__(self, credentials, use_sandbox=False, use_alternative_port=False, proto=None, json_encoder=None, password=None):
         if credentials is None or isinstance(credentials, str):
-            self.__credentials = CertificateCredentials(credentials)
+            self.__credentials = CertificateCredentials(credentials, password)
         else:
             self.__credentials = credentials
         self._init_connection(use_sandbox, use_alternative_port, proto)
diff --git a/apns2/credentials.py b/apns2/credentials.py
index a5bbdbd..a26a617 100644
--- a/apns2/credentials.py
+++ b/apns2/credentials.py
@@ -31,9 +31,9 @@ class Credentials(object):
 
 # Credentials subclass for certificate authentication
 class CertificateCredentials(Credentials):
-    def __init__(self, cert_file):
+    def __init__(self, cert_file, password=None):
         ssl_context = init_context()
-        ssl_context.load_cert_chain(cert_file)
+        ssl_context.load_cert_chain(cert_file, password=password)
         super(CertificateCredentials, self).__init__(ssl_context)