diff --git a/ortools/lp_data/lp_decomposer.cc b/ortools/lp_data/lp_decomposer.cc
index c9d5e1a576..31f45a0528 100644
--- a/ortools/lp_data/lp_decomposer.cc
+++ b/ortools/lp_data/lp_decomposer.cc
@@ -18,6 +18,7 @@
 
 #include "absl/log/check.h"
 #include "absl/synchronization/mutex.h"
+#include "absl/types/span.h"
 #include "ortools/algorithms/dynamic_partition.h"
 #include "ortools/lp_data/lp_data.h"
 #include "ortools/lp_data/lp_types.h"
@@ -139,7 +140,7 @@ void LPDecomposer::ExtractLocalProblem(int problem_index, LinearProgram* lp) {
 }
 
 DenseRow LPDecomposer::AggregateAssignments(
-    const std::vector<DenseRow>& assignments) const {
+    absl::Span<const DenseRow> assignments) const {
   CHECK_EQ(assignments.size(), clusters_.size());
 
   absl::MutexLock mutex_lock(&mutex_);
diff --git a/ortools/lp_data/lp_decomposer.h b/ortools/lp_data/lp_decomposer.h
index 8e5ee4993c..f583ee1d64 100644
--- a/ortools/lp_data/lp_decomposer.h
+++ b/ortools/lp_data/lp_decomposer.h
@@ -19,6 +19,7 @@
 
 #include "absl/base/thread_annotations.h"
 #include "absl/synchronization/mutex.h"
+#include "absl/types/span.h"
 #include "ortools/lp_data/lp_data.h"
 #include "ortools/lp_data/lp_types.h"
 
@@ -76,7 +77,7 @@ class LPDecomposer {
 
   // Returns an assignment to the original problem based on the assignments
   // to the independent problems. Requires Decompose() to have been called.
-  DenseRow AggregateAssignments(const std::vector<DenseRow>& assignments) const
+  DenseRow AggregateAssignments(absl::Span<const DenseRow> assignments) const
       ABSL_LOCKS_EXCLUDED(mutex_);
 
   // Returns an assignment to the given subproblem based on the assignment to