UNITED STATES SECURITIES AND EXCHANGE COMMISSION
 Washington, D.C. 20549
 
 FORM 10-K/A
 
 (Mark One)
 þANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2019
 OR
 ☐TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from ___________ to _________
 Commission File Number 001-37670
 
 Lonestar Resources US Inc.
 (Exact name of Registrant as specified in its Charter )
 
 Delaware81-0874035(State or other jurisdiction ofincorporation or organization)(I.R.S. EmployerIdentification No.)111 Boland Street, Suite 301, Fort Worth, TX76107(Address of principal executive offices)(Zip Code)
 Registrant’s telephone number, including area code: (817) 921-1889
 
 Securities Registered Pursuant to Section 12(b) of the Act:
 Title of Each ClassTrading SymbolName of Exchange on Which RegisteredClass A Voting Common Stock,par value $0.001 per shareLONENASDAQ Global Select Market
 Securities registered pursuant to Section 12(g) of the Act: None
 Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. YES ☐ NO þ
 Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Act. YES ☐ NO þ
 Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. . YES þ NO ☐
 Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).  . YES þ NO ☐
 Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.
 Large accelerated filer☐Accelerated filer☐Non-accelerated filerþSmaller reporting companyþEmerging growth companyþ
 If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐
 Indicate by check mark whether the Registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). YES ☐ NO þ
 The aggregate market value of the registrant’s Class A voting common stock held by non-affiliates, based on the closing price of the registrant’s Class A voting common stock as of the last business day of the registrant’s most recently completed second fiscal quarter, was approximately $45.3 million.
 The number of shares of the Registrant’s Class A voting common stock outstanding as of April 6, 2020 was 25,270,595.
 DOCUMENTS INCORPORATED BY REFERENCE
 Portions of the definitive proxy statement relating to the Registrant’s 2020 Annual Meeting of Shareholders are incorporated by reference into Part III of this Annual Report on Form 10-K.
 
 
 
 
  
 
 EXPLANATORY NOTE
 
 Lonestar Resources US Inc. (the “Company”) is filing this Amendment No. 1 on Form 10-K/A (the “Amendment”) to amend its Annual Report on Form 10-K for the year ended December 31, 2019, originally filed with the Securities and Exchange Commission (the “SEC”) on April 13, 2020 (the “Original Form 10-K”), solely to disclose that the Company had filed the Original Form 10-K after the March 30, 2020 deadline applicable to the Company for the filing of a Form 10-K in reliance on the 45-day extension provided by an order issued by the SEC under Section 36 of the Securities Exchange Act of 1934 Modifying Exemptions From the Reporting and Proxy Delivery Requirements for Public Companies, dated March 25, 2020 (Release No. 34-88465) (the “Order”).
 
 On March 27, 2020, the Company filed a Current Report on Form 8-K to indicate its intention to rely on the Order for such extension. Consistent with the Company’s statements made in the Form 8-K, the Company was unable to file the Original Form 10-K until April 13, 2020, and therefore relied on the Order, because, during the week of March 22, 2020, Tarrant County, Dallas County and Denton County (all counties in the state of Texas) issued various orders limiting the Company's ability to conduct its normal business operations, including orders to "shelter-in-place". The Company’s headquarters, officers, corporate, legal and accounting personnel, as well as certain of the Company's professional advisors are all located in these counties. The disruptions in staffing, communications and access to personnel resulted in delays, limited support and insufficient review. This, in turn, delayed the Company’s ability to complete its financial reporting process and prepare the Report.
 
 In accordance with Rules 12b-15 and 13a-14 under the Exchange Act of 1934, as amended, the Company is including in this Amendment currently dated certifications pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 from the Company’s principal executive officer and principal financial officer. Because no financial statements have been included in this Amendment and this Amendment does not contain or amend any disclosure with respect to Items 307 and 308 of Regulation S-K, paragraphs 3, 4 and 5 of the certifications have been omitted. Because no financial statements have been included in this Amendment, certifications pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 have been omitted.
 
 Except as described above, this Amendment does not amend, modify or update the information or disclosures in, or exhibits to, the Original Form 10-K. Furthermore, this Amendment does not change any previously reported financial results, nor does it reflect events occurring after the filing of the Original Form 10-K. Accordingly, this Amendment should be read in conjunction with the Original Form 10-K and the Company’s filings with the SEC subsequent to the filing of the Original Form 10-K.
 
 
 SIGNATURES
 
 Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.
 
 LONESTAR RESOURCES US INC.May 14, 2020By:/s/ Frank D. Bracken, IIIFrank D. Bracken, IIIChief Executive Officer
 
 
 
  
 
 Part IV.
 Item 15 (b). Exhibits
 The following exhibits are filed as a part of this report:
 
 Exhibit No.31.1Certification of Principal Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.31.2Certification of Principal Financial Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.