Kirkland Lake Gold Ltd. announced a revised drill intercept for one drill hole reported in the Lower Phoenix System at Fosterville in the news release issued on August 30, 2021. All other intercepts reported that August 30th News Release are unchanged. The drilling results and collar information for drill hole UDH4051 are presented in Tables 1 and 2. The drill result initially reported for the Lower Phoenix VG intercept was 51.7 g/t Au over 2.6 m (ETW 2.2 m), including 215 g/t over 0.6 m (ETW 0.5 m) in hole UDH4051. However, the revised intercept is 207 g/t Au over 2.6 m (ETW 2.2 m), including 947 g/t Au over 0.6 m (ETW 0.5 m). The grade revision for the intercept represents a four-fold increase from the previously reported result. The revision followed additional review of the assays released on August 30, 2021 from the Fosterville mine and resulted from an analytical error at independent assay laboratory, On Site Laboratory Services. The error in the initial report was identified during a subsequent review of the sample batch, which was assayed using an Atomic Absorption Spectrometry (AAS) instrument to measure gold in solutions. The analytical method required solutions for extremely high-grade gold samples to be diluted, and dilution calculations applied to the AAS readings to return the gold assay. On Site Laboratory Services identified that a transcription error had occurred, and that a dilution calculation had not been applied to two results in their initial report. Comparable results for the updated UDH4051 intercept have since been returned for screen fire (metallic screening) assay, and the Chrysos PhotonAssay techniques. Drilling and Underground Sampling Assay QAQC: Kirkland Lake Gold has in place quality-control systems to ensure best practice in drilling, sampling and analysis of drill core. All underground diamond drill hole collars are accurately surveyed using a Leica TS16 Total Station. Down-hole deviations are measured by either electronic gyro or single-shot instruments. Sampling of diamond drill hole UDH4051 consisted of full core sampled that was sent to an independent laboratory for analysis. Sample pulps are returned from the assay laboratory for reference and future geological or metallurgical studies. Drill core sample intervals vary between 0.1 and 1.0m in length and were determined from logging of sulfide and VG to geological boundaries. For assay QAQC purposes Certified Reference Material (CRM) and Blank samples are inserted into the sample stream at rates of approximately 1 in 25. Samples containing visible-gold or considered likely to contain visible-gold were separated from sulfide gold samples and dispatched separately for assaying. At the laboratory "visible-gold" jobs were processed through a single pulverizer and material barren of gold ('quartz wash') was crushed before and after each sample to minimize the potential for gold to contaminate successive samples. Assays are based on a 25-gram fire assay method. Samples containing VG or returning high-grade fire assay results are also verified by Screen fire assaying (metallic screening) with either Atomic Absorption Spectroscopy (AAS) or Gravimetric finish. Mean grades are calculated using a variable lower grade cut-off (generally 2 g/t Au) and maximum 2 m internal dilution. No upper gold grade cut-off is applied to the data. However, during future Mineral Resource studies the requirement for assay top cutting will be assessed. The samples were assayed at On Site Laboratory Services, an independent laboratory in Bendigo, Victoria. The facility is registered under ISO 9001:2015 (CERT-40147) and operates in accordance with ISO/IEC17025 (accreditation no. 20456) under National Association of Testing Authorities, Australia (NATA).