diff --git a/examples/slam/pose_graph_3d/pose_graph_3d.cc b/examples/slam/pose_graph_3d/pose_graph_3d.cc
index c7c47fd7c..191758d68 100644
--- a/examples/slam/pose_graph_3d/pose_graph_3d.cc
+++ b/examples/slam/pose_graph_3d/pose_graph_3d.cc
@@ -34,6 +34,7 @@
 
 #include "ceres/ceres.h"
 #include "common/read_g2o.h"
+#include "gflags/gflags.h"
 #include "glog/logging.h"
 #include "pose_graph_3d_error_term.h"
 #include "types.h"
diff --git a/include/ceres/cost_function_to_functor.h b/include/ceres/cost_function_to_functor.h
index 6c67ac0f9..d2dc94725 100644
--- a/include/ceres/cost_function_to_functor.h
+++ b/include/ceres/cost_function_to_functor.h
@@ -130,7 +130,8 @@ class CostFunctionToFunctor {
     const int num_parameter_blocks =
         (N0 > 0) + (N1 > 0) + (N2 > 0) + (N3 > 0) + (N4 > 0) +
         (N5 > 0) + (N6 > 0) + (N7 > 0) + (N8 > 0) + (N9 > 0);
-    CHECK_EQ(parameter_block_sizes.size(), num_parameter_blocks);
+    CHECK_EQ(static_cast<int>(parameter_block_sizes.size()),
+             num_parameter_blocks);
 
     CHECK_EQ(N0, parameter_block_sizes[0]);
     if (parameter_block_sizes.size() > 1) CHECK_EQ(N1, parameter_block_sizes[1]);  // NOLINT
diff --git a/include/ceres/dynamic_numeric_diff_cost_function.h b/include/ceres/dynamic_numeric_diff_cost_function.h
index 7f0a9510e..5770946a1 100644
--- a/include/ceres/dynamic_numeric_diff_cost_function.h
+++ b/include/ceres/dynamic_numeric_diff_cost_function.h
@@ -122,19 +122,19 @@ class DynamicNumericDiffCostFunction : public CostFunction {
     std::vector<double> parameters_copy(parameters_size);
     std::vector<double*> parameters_references_copy(block_sizes.size());
     parameters_references_copy[0] = &parameters_copy[0];
-    for (int block = 1; block < block_sizes.size(); ++block) {
+    for (size_t block = 1; block < block_sizes.size(); ++block) {
       parameters_references_copy[block] = parameters_references_copy[block - 1]
           + block_sizes[block - 1];
     }
 
     // Copy the parameters into the local temp space.
-    for (int block = 0; block < block_sizes.size(); ++block) {
+    for (size_t block = 0; block < block_sizes.size(); ++block) {
       memcpy(parameters_references_copy[block],
              parameters[block],
              block_sizes[block] * sizeof(*parameters[block]));
     }
 
-    for (int block = 0; block < block_sizes.size(); ++block) {
+    for (size_t block = 0; block < block_sizes.size(); ++block) {
       if (jacobians[block] != NULL &&
           !NumericDiff<CostFunctor, method, DYNAMIC,
                        DYNAMIC, DYNAMIC, DYNAMIC, DYNAMIC, DYNAMIC,