6. Restricted Cash

At December 31, 2018, the Company had $0.9 million in restricted cash, of which $0.6 million was classified as short-term and $0.3 million as long-term on the Company’s consolidated balance sheets. At December 31, 2017, the Company had $0.5 million in restricted cash, of which $0.2 million was classified as short-term and $0.3 million as long-term on the Company’s consolidated balance sheets.

As of December 31, 2017, the $0.5 million of restricted cash served as the security deposit on the lease of the Company’s current facility in Cambridge, Massachusetts (see Note 10). In April 2018, the Company collected a $0.2 million refund from its landlord in accordance with the terms of the lease agreement and the remaining of $0.3 million is classified as long-term on the Company’s consolidated balance sheets as of December 31, 2018.

In August 2018, the Company entered into a manufacturing agreement with a third party for manufacturing services related to one of its product candidates. In accordance with the terms of the manufacturing agreement, the Company was required to provide a letter of credit in the amount of $0.6 million. The letter of credit will expire on September 30, 2019 and is classified as short-term on the Company’s consolidated balance sheets as of December 31, 2018.

In accordance with the recently adopted accounting pronouncement ASU 2016-18, the following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the consolidated balance sheets that sum to the total of the amounts shown in the consolidated statement of cash flows as of December 31, 2018, 2017, 2016 and 2015 (in thousands):