diff --git a/ortools/algorithms/BUILD.bazel b/ortools/algorithms/BUILD.bazel
index e38936416d..1e5a4f12fa 100644
--- a/ortools/algorithms/BUILD.bazel
+++ b/ortools/algorithms/BUILD.bazel
@@ -166,6 +166,7 @@ cc_test(
         "//ortools/base:types",
         "@com_google_absl//absl/container:flat_hash_map",
         "@com_google_absl//absl/random:distributions",
+        "@com_google_absl//absl/types:span",
     ],
 )
 
diff --git a/ortools/algorithms/hungarian_test.cc b/ortools/algorithms/hungarian_test.cc
index 78cb65729a..bb2c196454 100644
--- a/ortools/algorithms/hungarian_test.cc
+++ b/ortools/algorithms/hungarian_test.cc
@@ -22,6 +22,7 @@
 
 #include "absl/container/flat_hash_map.h"
 #include "absl/random/distributions.h"
+#include "absl/types/span.h"
 #include "gtest/gtest.h"
 #include "ortools/base/macros.h"
 #include "ortools/base/map_util.h"
@@ -51,7 +52,7 @@ void GenericCheck(const int expected_assignment_size,
   }
 }
 
-void TestMinimization(const std::vector<std::vector<double>>& cost,
+void TestMinimization(absl::Span<const std::vector<double>> cost,
                       const int expected_assignment_size,
                       const int expected_agents[], const int expected_tasks[]) {
   absl::flat_hash_map<int, int> direct_assignment;
@@ -62,7 +63,7 @@ void TestMinimization(const std::vector<std::vector<double>>& cost,
                expected_agents, expected_tasks);
 }
 
-void TestMaximization(const std::vector<std::vector<double>>& cost,
+void TestMaximization(absl::Span<const std::vector<double>> cost,
                       const int expected_assignment_size,
                       const int expected_agents[], const int expected_tasks[]) {
   absl::flat_hash_map<int, int> direct_assignment;
diff --git a/ortools/graph/cliques_test.cc b/ortools/graph/cliques_test.cc
index 37b4db82a9..d846be1d65 100644
--- a/ortools/graph/cliques_test.cc
+++ b/ortools/graph/cliques_test.cc
@@ -85,7 +85,7 @@ class CliqueSizeVerifier {
   }
 
   std::function<CliqueResponse(const std::vector<int>&)> MakeCliqueCallback() {
-    return [this](const std::vector<int>& clique) {
+    return [this](absl::Span<const int> clique) {
       return AppendClique(clique) ? CliqueResponse::STOP
                                   : CliqueResponse::CONTINUE;
     };
diff --git a/ortools/graph/hamiltonian_path_test.cc b/ortools/graph/hamiltonian_path_test.cc
index e551de9ee1..ffaa436c9f 100644
--- a/ortools/graph/hamiltonian_path_test.cc
+++ b/ortools/graph/hamiltonian_path_test.cc
@@ -23,6 +23,7 @@
 
 #include "absl/random/distributions.h"
 #include "absl/strings/str_format.h"
+#include "absl/types/span.h"
 #include "gtest/gtest.h"
 #include "ortools/base/logging.h"
 #include "ortools/base/macros.h"
@@ -92,7 +93,7 @@ TEST(LatticeMemoryManagerTest, Offset) {
 }
 
 // Displays the path.
-std::string PathToString(const std::vector<int>& path) {
+std::string PathToString(absl::Span<const int> path) {
   std::string path_string;
   const int size = path.size();
   for (int i = 0; i < size; i++) {
diff --git a/ortools/graph/max_flow_test.cc b/ortools/graph/max_flow_test.cc
index 0538f28b20..05784665bb 100644
--- a/ortools/graph/max_flow_test.cc
+++ b/ortools/graph/max_flow_test.cc
@@ -586,7 +586,7 @@ void PartialRandomAssignment(typename MaxFlowSolver<Graph>::Solver f,
 }
 
 template <typename Graph>
-void ChangeCapacities(const std::vector<int64_t>& arc_capacity,
+void ChangeCapacities(absl::Span<const int64_t> arc_capacity,
                       FlowQuantity delta, GenericMaxFlow<Graph>* max_flow) {
   const Graph* graph = max_flow->graph();
   for (typename Graph::ArcIndex arc = 0; arc < graph->num_arcs(); ++arc) {
diff --git a/ortools/util/fp_utils.cc b/ortools/util/fp_utils.cc
index 8ca04d1432..98854d8a05 100644
--- a/ortools/util/fp_utils.cc
+++ b/ortools/util/fp_utils.cc
@@ -194,7 +194,7 @@ double GetBestScalingOfDoublesToInt64(absl::Span<const double> input,
   return scaling_factor;
 }
 
-void GetBestScalingOfDoublesToInt64(const std::vector<double>& input,
+void GetBestScalingOfDoublesToInt64(absl::Span<const double> input,
                                     int64_t max_absolute_sum,
                                     double* scaling_factor,
                                     double* max_relative_coeff_error) {
diff --git a/ortools/util/fp_utils.h b/ortools/util/fp_utils.h
index 884b46a514..34e0a0d8e7 100644
--- a/ortools/util/fp_utils.h
+++ b/ortools/util/fp_utils.h
@@ -207,7 +207,7 @@ inline bool IsIntegerWithinTolerance(FloatType x, FloatType tolerance) {
 //
 // TODO(user): incorporate the gcd computation here? The issue is that I am
 // not sure if I just do factor /= gcd that round(x * factor) will be the same.
-void GetBestScalingOfDoublesToInt64(const std::vector<double>& input,
+void GetBestScalingOfDoublesToInt64(absl::Span<const double> input,
                                     int64_t max_absolute_sum,
                                     double* scaling_factor,
                                     double* max_relative_coeff_error);