diff --git a/buildman/builder.py b/buildman/builder.py
index 3e14db3eb..4f0d8f2d7 100644
--- a/buildman/builder.py
+++ b/buildman/builder.py
@@ -44,8 +44,8 @@ def run_build_manager():
   if os.environ.get('SSL_CONFIG'):
     logger.debug('Loading SSL cert and key')
     ssl_context = SSLContext()
-    ssl_context.load_cert_chain(os.environ.get('SSL_CONFIG') + '/ssl.cert',
-                                os.environ.get('SSL_CONFIG') + '/ssl.key')
+    ssl_context.load_cert_chain(os.path.join(os.environ.get('SSL_CONFIG'), 'ssl.cert'),
+                                os.path.join(os.environ.get('SSL_CONFIG'), 'ssl.key'))
 
   server = BuilderServer(app.config['SERVER_HOSTNAME'], dockerfile_build_queue, build_logs,
                          user_files, manager_klass)