diff --git a/src/lib/pbkdf/pgp_s2k/pgp_s2k.cpp b/src/lib/pbkdf/pgp_s2k/pgp_s2k.cpp
index d04fb47b36a..8bcf9239fcc 100644
--- a/src/lib/pbkdf/pgp_s2k/pgp_s2k.cpp
+++ b/src/lib/pbkdf/pgp_s2k/pgp_s2k.cpp
@@ -61,7 +61,7 @@ uint8_t RFC4880_encode_count(size_t desired_iterations)
    if(desired_iterations >= OPENPGP_S2K_ITERS[255])
       return 255;
 
-   auto i = std::upper_bound(OPENPGP_S2K_ITERS, OPENPGP_S2K_ITERS + 256, desired_iterations);
+   auto i = std::lower_bound(OPENPGP_S2K_ITERS, OPENPGP_S2K_ITERS + 256, desired_iterations);
 
    return static_cast<uint8_t>(i - OPENPGP_S2K_ITERS);
    }