diff --git a/cpp/include/raft/spectral/detail/matrix_wrappers.hpp b/cpp/include/raft/spectral/detail/matrix_wrappers.hpp
index 07ab1dbeba..c756a3f097 100644
--- a/cpp/include/raft/spectral/detail/matrix_wrappers.hpp
+++ b/cpp/include/raft/spectral/detail/matrix_wrappers.hpp
@@ -30,6 +30,8 @@
 #include <thrust/reduce.h>
 #include <thrust/system/cuda/execution_policy.h>
 
+#include <cuda/functional>
+
 #include <algorithm>
 
 // =========================================================
@@ -111,11 +113,11 @@ class vector_t {
                           buffer_.data(),
                           buffer_.data() + buffer_.size(),
                           value_type{0},
-                          [] __device__(auto left, auto right) {
+                          cuda::proclaim_return_type<value_type>([] __device__(auto left, auto right) {
                             auto abs_left  = left > 0 ? left : -left;
                             auto abs_right = right > 0 ? right : -right;
                             return abs_left + abs_right;
-                          });
+                          }));
   }
 
   void fill(value_type value)