Miguel Angel Madrigal pleaded guilty to one count of possession of more than 100 kilograms of marijuana with intent to distribute in violation of 21 U.S.C. § 841(a)(1), (b)(1)(B). He now appeals the district court’s denial of a so-called safety valve reduction pursuant to U.S.S.G. § 5C1.2. Finding no error, we affirm.

Of the five criteria for a § 5C1.2 adjustment, the only one at issue here is the requirement that the defendant has truthfully provided the Government with all information and evidence he has concerning the offense. We review the district court’s factual finding that Madrigal did not truthfully debrief for clear error. See United States v. Miller, 179 F.3d 961, 963-64 (5th Cir.1999).

Contrary to Madrigal’s assertions, the district court’s conclusion was not based on unsubstantiated speculation. Rather, the district court heard directly from Madrigal and concluded that his story that a stranger sought him out randomly to transport a large and valuable load of marijuana for $10,000 was not plausible. The district court’s credibility determination, entitled to great deference, was not clearly erroneous. United States v. Powers, 168 F.3d 741, 753 (5th Cir.1999); United States v. Miller, 179 F.3d 961, 968 (5th Cir.1999); United States v. Salinas-Capistran, 133 Fed. App’x 112, 113-14 (5th Cir.2005).

Accordingly, the judgment of the district court is AFFIRMED.