diff --git a/jupyter-openbis-extension/static/connectionDialog.js b/jupyter-openbis-extension/static/connectionDialog.js
index 81eed5fdc8fb3d4fb9265f28996fe956078b3eaa..ea1c86d4de8717ec2d8095881136d12c60f98f69 100644
--- a/jupyter-openbis-extension/static/connectionDialog.js
+++ b/jupyter-openbis-extension/static/connectionDialog.js
@@ -231,7 +231,13 @@ define(
             // by combining the notebook_dir (from the jupyter configuration) and the relative notebook_path
             let re = new RegExp(env.notebook.notebook_name+"$")
             rel_path = env.notebook.notebook_path.replace(re, "")
-            let default_working_dir = data.notebook_dir + "/" + rel_path
+            let default_working_dir = ""
+            if (data.notebook_dir.endsWith('/')) {
+                default_working_dir = data.notebook_dir + rel_path
+            }
+            else {
+                default_working_dir = data.notebook_dir + "/" + rel_path
+            }
 
             working_dir_in.value = state.working_dir ? state.working_dir : default_working_dir
             state.working_dir_element = working_dir_in