diff --git a/cub/agent/single_pass_scan_operators.cuh b/cub/agent/single_pass_scan_operators.cuh
index b32b95234..ac1c61d27 100644
--- a/cub/agent/single_pass_scan_operators.cuh
+++ b/cub/agent/single_pass_scan_operators.cuh
@@ -783,6 +783,7 @@ struct TilePrefixCallbackOp
     {}
 
     // Computes the tile index and constructs prefix functor with it.
+    // Precondition: thread block per tile assignment.
     __device__ __forceinline__ TilePrefixCallbackOp(ScanTileStateT &tile_status,
                                                     TempStorage &temp_storage,
                                                     ScanOpT scan_op)