diff --git a/pybiopax/pc_client.py b/pybiopax/pc_client.py
index 41dec4b..65a93a7 100644
--- a/pybiopax/pc_client.py
+++ b/pybiopax/pc_client.py
@@ -6,7 +6,7 @@
 import requests
 
 logger = logging.getLogger(__name__)
-pc2_url = 'http://www.pathwaycommons.org/pc2/'
+pc2_url = 'https://www.pathwaycommons.org/pc2/'
 
 
 def graph_query(kind, source, target=None, **query_params):