Update erpnext/selling/doctype/sales_common/sales_common.js
diff --git a/erpnext/selling/doctype/sales_common/sales_common.js b/erpnext/selling/doctype/sales_common/sales_common.js
index a3470ec..5dcdb69 100644
--- a/erpnext/selling/doctype/sales_common/sales_common.js
+++ b/erpnext/selling/doctype/sales_common/sales_common.js
@@ -163,7 +163,7 @@
 					if (pl_currency[0] == doc.currency) {
 						set_multiple(cdt, cdn, {price_list_currency:doc.currency, plc_conversion_rate:doc.conversion_rate});
 						hide_field(['price_list_currency', 'plc_conversion_rate']);
-					} else if (pl_currency[0] = r.message[1]) {
+					} else if (pl_currency[0] == r.message[1]) {
 						set_multiple(cdt, cdn, {price_list_currency:pl_currency[0], plc_conversion_rate:1})
 						hide_field(['price_list_currency', 'plc_conversion_rate']);
 					}