diff --git a/erpnext/projects/doctype/task/task.py b/erpnext/projects/doctype/task/task.py
index 9b1ea04..8fa0538 100755
--- a/erpnext/projects/doctype/task/task.py
+++ b/erpnext/projects/doctype/task/task.py
@@ -102,7 +102,7 @@
 			frappe.throw(_("Completed On cannot be greater than Today"))
 
 	def update_depends_on(self):
-		depends_on_tasks = self.depends_on_tasks or ""
+		depends_on_tasks = ""
 		for d in self.depends_on:
 			if d.task and d.task not in depends_on_tasks:
 				depends_on_tasks += d.task + ","