diff --git a/cpp/include/cudf/ast/detail/operators.hpp b/cpp/include/cudf/ast/detail/operators.hpp
index db04e1fe989..5165ef6e895 100644
--- a/cpp/include/cudf/ast/detail/operators.hpp
+++ b/cpp/include/cudf/ast/detail/operators.hpp
@@ -21,8 +21,8 @@
 #include <cudf/utilities/error.hpp>
 #include <cudf/utilities/type_dispatcher.hpp>
 
+#include <cuda/std/optional>
 #include <cuda/std/type_traits>
-#include <thrust/optional.h>
 
 #include <cmath>
 #include <type_traits>
@@ -35,14 +35,14 @@ namespace ast {
 
 namespace detail {
 
-// Type trait for wrapping nullable types in a thrust::optional. Non-nullable
+// Type trait for wrapping nullable types in a cuda::std::optional. Non-nullable
 // types are returned as is.
 template <typename T, bool has_nulls>
 struct possibly_null_value;
 
 template <typename T>
 struct possibly_null_value<T, true> {
-  using type = thrust::optional<T>;
+  using type = cuda::std::optional<T>;
 };
 
 template <typename T>
diff --git a/cpp/src/io/avro/reader_impl.cu b/cpp/src/io/avro/reader_impl.cu
index f0a92f7554d..11d5749ee38 100644
--- a/cpp/src/io/avro/reader_impl.cu
+++ b/cpp/src/io/avro/reader_impl.cu
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020-2024, NVIDIA CORPORATION.
+ * Copyright (c) 2020-2025, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -303,7 +303,7 @@ rmm::device_buffer decompress_data(datasource& source,
     size_t const max_uncomp_block_size = std::reduce(
       uncompressed_data_sizes.begin(), uncompressed_data_sizes.end(), 0, thrust::maximum<size_t>());
 
-    size_t temp_size;
+    size_t temp_size = 0;
     status =
       nvcompBatchedSnappyDecompressGetTempSize(num_blocks, max_uncomp_block_size, &temp_size);
     CUDF_EXPECTS(status == nvcompStatus_t::nvcompSuccess,
diff --git a/cpp/src/quantiles/tdigest/tdigest_aggregation.cu b/cpp/src/quantiles/tdigest/tdigest_aggregation.cu
index 2128bacff80..fd98d262154 100644
--- a/cpp/src/quantiles/tdigest/tdigest_aggregation.cu
+++ b/cpp/src/quantiles/tdigest/tdigest_aggregation.cu
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021-2024, NVIDIA CORPORATION.
+ * Copyright (c) 2021-2025, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -1088,7 +1088,7 @@ std::pair<rmm::device_uvector<double>, rmm::device_uvector<double>> generate_mer
         size_type i) { return tdigest_offsets[group_offsets[i]]; }));
 
   // perform the sort using the means as the key
-  size_t temp_size;
+  size_t temp_size = 0;
   CUDF_CUDA_TRY(cub::DeviceSegmentedSort::SortPairs(nullptr,
                                                     temp_size,
                                                     tdv.means().begin<double>(),