diff --git a/erpnext/loan_management/doctype/loan/loan.py b/erpnext/loan_management/doctype/loan/loan.py
index 578c7f116a..2e0a4d13ab 100644
--- a/erpnext/loan_management/doctype/loan/loan.py
+++ b/erpnext/loan_management/doctype/loan/loan.py
@@ -6,6 +6,7 @@ from __future__ import unicode_literals
 import frappe, math, json
 import erpnext
 from frappe import _
+from six import string_types
 from frappe.utils import flt, rounded, add_months, nowdate, getdate, now_datetime
 from erpnext.loan_management.doctype.loan_security_unpledge.loan_security_unpledge import get_pledged_security_qty
 from erpnext.controllers.accounts_controller import AccountsController
@@ -282,6 +283,9 @@ def make_loan_write_off(loan, company=None, posting_date=None, amount=0, as_dict
 @frappe.whitelist()
 def unpledge_security(loan=None, loan_security_pledge=None, security_map=None, as_dict=0, save=0, submit=0, approve=0):
 	# if no security_map is passed it will be considered as full unpledge
+	if security_map and isinstance(security_map, string_types):
+		security_map = json.loads(security_map)
+
 	if loan:
 		pledge_qty_map = security_map or get_pledged_security_qty(loan)
 		loan_doc = frappe.get_doc('Loan', loan)