Exhibit 99.12

CONSENT OF GEOLOGIST

Ladies and Gentlemen:

The undersigned hereby consents to (1) the references to the undersigned’s name included or incorporated by reference in the Annual Report on Form 40-F of Denison Mines Corp. and the registration statements on Forms S-8 (File Nos. 333-190121 and 333-224641) of Denison Mines Corp. (the “Registration Statements”), including in connection with the report entitled “Technical Report with an Updated Mineral Resource Estimate for the Midwest Property, Northern Saskatchewan, Canada” dated March 26, 2018 (the “Technical Report”), and (2) all other references to the undersigned included or incorporated by reference in the Annual Report on Form 40-F of Denison Mines Corp. and the Registration Statements and to the inclusion and incorporation by reference of the information derived from the Technical Report in the Annual Report on Form 40-F and the Registration Statements.

Dated: March 28, 2024

/s/ Dale Verran

Dale Verran, MSc, P.Geo., Pr.Sci.Nat.