diff --git a/examples/slam/common/read_g2o.h b/examples/slam/common/read_g2o.h
index fea32e9..255a27d 100644
--- a/examples/slam/common/read_g2o.h
+++ b/examples/slam/common/read_g2o.h
@@ -104,8 +104,8 @@
 bool ReadG2oFile(const std::string& filename,
                  std::map<int, Pose, std::less<int>, MapAllocator>* poses,
                  std::vector<Constraint, VectorAllocator>* constraints) {
-  CHECK(poses != NULL);
-  CHECK(constraints != NULL);
+  CHECK(poses != nullptr);
+  CHECK(constraints != nullptr);
 
   poses->clear();
   constraints->clear();
diff --git a/include/ceres/autodiff_local_parameterization.h b/include/ceres/autodiff_local_parameterization.h
index ac2b5e3..5f9b04d 100644
--- a/include/ceres/autodiff_local_parameterization.h
+++ b/include/ceres/autodiff_local_parameterization.h
@@ -137,7 +137,7 @@
     }
 
     const double* parameter_ptrs[2] = {x, zero_delta};
-    double* jacobian_ptrs[2] = {NULL, jacobian};
+    double* jacobian_ptrs[2] = {nullptr, jacobian};
     return internal::AutoDifferentiate<
         kGlobalSize,
         internal::StaticParameterDims<kGlobalSize, kLocalSize>>(
diff --git a/include/ceres/conditioned_cost_function.h b/include/ceres/conditioned_cost_function.h
index 8690c83..e80728d 100644
--- a/include/ceres/conditioned_cost_function.h
+++ b/include/ceres/conditioned_cost_function.h
@@ -76,7 +76,7 @@
   // Builds a cost function based on a wrapped cost function, and a
   // per-residual conditioner. Takes ownership of all of the wrapped cost
   // functions, or not, depending on the ownership parameter. Conditioners
-  // may be NULL, in which case the corresponding residual is not modified.
+  // may be nullptr, in which case the corresponding residual is not modified.
   //
   // The conditioners can repeat.
   ConditionedCostFunction(CostFunction* wrapped_cost_function,
diff --git a/include/ceres/cost_function.h b/include/ceres/cost_function.h
index a904a2b..1bf687c 100644
--- a/include/ceres/cost_function.h
+++ b/include/ceres/cost_function.h
@@ -92,8 +92,8 @@
   //   jacobians[i][r*parameter_block_size_[i] + c] =
   //                              d residual[r] / d parameters[i][c]
   //
-  // If jacobians is NULL, then no derivatives are returned; this is
-  // the case when computing cost only. If jacobians[i] is NULL, then
+  // If jacobians is nullptr, then no derivatives are returned; this is
+  // the case when computing cost only. If jacobians[i] is nullptr, then
   // the jacobian block corresponding to the i'th parameter block must
   // not to be returned.
   //
diff --git a/include/ceres/cubic_interpolation.h b/include/ceres/cubic_interpolation.h
index 9b9ea4a..fb2f998 100644
--- a/include/ceres/cubic_interpolation.h
+++ b/include/ceres/cubic_interpolation.h
@@ -59,8 +59,8 @@
 // http://en.wikipedia.org/wiki/Cubic_Hermite_spline
 // http://en.wikipedia.org/wiki/Bicubic_interpolation
 //
-// f if not NULL will contain the interpolated function values.
-// dfdx if not NULL will contain the interpolated derivative values.
+// f if not nullptr will contain the interpolated function values.
+// dfdx if not nullptr will contain the interpolated derivative values.
 template <int kDataDimension>
 void CubicHermiteSpline(const Eigen::Matrix<double, kDataDimension, 1>& p0,
                         const Eigen::Matrix<double, kDataDimension, 1>& p1,
@@ -79,12 +79,12 @@
   // derivative.
 
   // f = ax^3 + bx^2 + cx + d
-  if (f != NULL) {
+  if (f != nullptr) {
     Eigen::Map<VType>(f, kDataDimension) = d + x * (c + x * (b + x * a));
   }
 
   // dfdx = 3ax^2 + 2bx + c
-  if (dfdx != NULL) {
+  if (dfdx != nullptr) {
     Eigen::Map<VType>(dfdx, kDataDimension) = c + x * (2.0 * b + 3.0 * a * x);
   }
 }
@@ -143,7 +143,7 @@
   // The following two Evaluate overloads are needed for interfacing
   // with automatic differentiation. The first is for when a scalar
   // evaluation is done, and the second one is for when Jets are used.
-  void Evaluate(const double& x, double* f) const { Evaluate(x, f, NULL); }
+  void Evaluate(const double& x, double* f) const { Evaluate(x, f, nullptr); }
 
   template <typename JetT>
   void Evaluate(const JetT& x, JetT* f) const {
@@ -317,10 +317,10 @@
     // Interpolate vertically the interpolated value from each row and
     // compute the derivative along the columns.
     CubicHermiteSpline<Grid::DATA_DIMENSION>(f0, f1, f2, f3, r - row, f, dfdr);
-    if (dfdc != NULL) {
+    if (dfdc != nullptr) {
       // Interpolate vertically the derivative along the columns.
       CubicHermiteSpline<Grid::DATA_DIMENSION>(
-          df0dc, df1dc, df2dc, df3dc, r - row, dfdc, NULL);
+          df0dc, df1dc, df2dc, df3dc, r - row, dfdc, nullptr);
     }
   }
 
@@ -328,7 +328,7 @@
   // with automatic differentiation. The first is for when a scalar
   // evaluation is done, and the second one is for when Jets are used.
   void Evaluate(const double& r, const double& c, double* f) const {
-    Evaluate(r, c, f, NULL, NULL);
+    Evaluate(r, c, f, nullptr, nullptr);
   }
 
   template <typename JetT>
diff --git a/include/ceres/dynamic_autodiff_cost_function.h b/include/ceres/dynamic_autodiff_cost_function.h
index 0531786..2812956 100644
--- a/include/ceres/dynamic_autodiff_cost_function.h
+++ b/include/ceres/dynamic_autodiff_cost_function.h
@@ -105,7 +105,7 @@
         << "You must call DynamicAutoDiffCostFunction::SetNumResiduals() "
         << "before DynamicAutoDiffCostFunction::Evaluate().";
 
-    if (jacobians == NULL) {
+    if (jacobians == nullptr) {
       return (*functor_)(parameters, residuals);
     }
 
@@ -150,7 +150,7 @@
       jet_parameters[i] = &input_jets[parameter_cursor];
 
       const int parameter_block_size = parameter_block_sizes()[i];
-      if (jacobians[i] != NULL) {
+      if (jacobians[i] != nullptr) {
         if (!in_derivative_section) {
           start_derivative_section.push_back(parameter_cursor);
           in_derivative_section = true;
@@ -209,7 +209,7 @@
               parameter_cursor >=
                   (start_derivative_section[current_derivative_section] +
                    current_derivative_section_cursor)) {
-            if (jacobians[i] != NULL) {
+            if (jacobians[i] != nullptr) {
               input_jets[parameter_cursor].v[active_parameter_count] = 1.0;
               ++active_parameter_count;
               ++current_derivative_section_cursor;
@@ -238,7 +238,7 @@
               parameter_cursor >=
                   (start_derivative_section[current_derivative_section] +
                    current_derivative_section_cursor)) {
-            if (jacobians[i] != NULL) {
+            if (jacobians[i] != nullptr) {
               for (int k = 0; k < num_residuals(); ++k) {
                 jacobians[i][k * parameter_block_sizes()[i] + j] =
                     output_jets[k].v[active_parameter_count];
diff --git a/include/ceres/dynamic_cost_function_to_functor.h b/include/ceres/dynamic_cost_function_to_functor.h
index 5f47875..2d28f97 100644
--- a/include/ceres/dynamic_cost_function_to_functor.h
+++ b/include/ceres/dynamic_cost_function_to_functor.h
@@ -110,7 +110,7 @@
   }
 
   bool operator()(double const* const* parameters, double* residuals) const {
-    return cost_function_->Evaluate(parameters, residuals, NULL);
+    return cost_function_->Evaluate(parameters, residuals, nullptr);
   }
 
   template <typename JetT>
diff --git a/include/ceres/dynamic_numeric_diff_cost_function.h b/include/ceres/dynamic_numeric_diff_cost_function.h
index ff02b40..9cbc8ee 100644
--- a/include/ceres/dynamic_numeric_diff_cost_function.h
+++ b/include/ceres/dynamic_numeric_diff_cost_function.h
@@ -111,7 +111,7 @@
     const bool status =
         internal::VariadicEvaluate<internal::DynamicParameterDims>(
             *functor_.get(), parameters, residuals);
-    if (jacobians == NULL || !status) {
+    if (jacobians == nullptr || !status) {
       return status;
     }
 
@@ -133,7 +133,7 @@
     }
 
     for (size_t block = 0; block < block_sizes.size(); ++block) {
-      if (jacobians[block] != NULL &&
+      if (jacobians[block] != nullptr &&
           !NumericDiff<CostFunctor,
                        method,
                        ceres::DYNAMIC,
diff --git a/include/ceres/gradient_checker.h b/include/ceres/gradient_checker.h
index b92a29d..8e4d06c 100644
--- a/include/ceres/gradient_checker.h
+++ b/include/ceres/gradient_checker.h
@@ -151,7 +151,7 @@
   // Jacobians. If the Jacobians differ by more than this amount, then the
   // probe fails.
   // results: On return, the Jacobians (and other information) will be stored
-  // here. May be NULL.
+  // here. May be nullptr.
   //
   // Returns true if no problems are detected and the difference between the
   // Jacobians is less than error_tolerance.
diff --git a/include/ceres/gradient_problem.h b/include/ceres/gradient_problem.h
index 08a58d0..b22d91a 100644
--- a/include/ceres/gradient_problem.h
+++ b/include/ceres/gradient_problem.h
@@ -78,7 +78,7 @@
 //     const double y = parameters[1];
 //
 //     cost[0] = (1.0 - x) * (1.0 - x) + 100.0 * (y - x * x) * (y - x * x);
-//     if (gradient != NULL) {
+//     if (gradient != nullptr) {
 //       gradient[0] = -2.0 * (1.0 - x) - 200.0 * (y - x * x) * 2.0 * x;
 //       gradient[1] = 200.0 * (y - x * x);
 //     }
diff --git a/include/ceres/internal/autodiff.h b/include/ceres/internal/autodiff.h
index 9d7de75..4a0c982 100644
--- a/include/ceres/internal/autodiff.h
+++ b/include/ceres/internal/autodiff.h
@@ -132,10 +132,10 @@
 // respectively. This is how autodiff works for functors taking multiple vector
 // valued arguments (up to 6).
 //
-// Jacobian NULL pointers
-// ----------------------
-// In general, the functions below will accept NULL pointers for all or some of
-// the Jacobian parameters, meaning that those Jacobians will not be computed.
+// Jacobian null pointers (nullptr)
+// --------------------------------
+// In general, the functions below will accept nullptr for all or some of the
+// Jacobian parameters, meaning that those Jacobians will not be computed.
 
 #ifndef CERES_PUBLIC_INTERNAL_AUTODIFF_H_
 #define CERES_PUBLIC_INTERNAL_AUTODIFF_H_
diff --git a/include/ceres/loss_function.h b/include/ceres/loss_function.h
index bc9d6a1..06c8bae 100644
--- a/include/ceres/loss_function.h
+++ b/include/ceres/loss_function.h
@@ -35,7 +35,7 @@
 //
 // For least squares problem where there are no outliers and standard
 // squared loss is expected, it is not necessary to create a loss
-// function; instead passing a NULL to the problem when adding
+// function; instead passing a nullptr to the problem when adding
 // residuals implies a standard squared loss.
 //
 // For least squares problems where the minimization may encounter
@@ -125,7 +125,7 @@
 //
 // At s = 0: rho = [0, 1, 0].
 //
-// It is not normally necessary to use this, as passing NULL for the
+// It is not normally necessary to use this, as passing nullptr for the
 // loss function when building the problem accomplishes the same
 // thing.
 class CERES_EXPORT TrivialLoss : public LossFunction {
@@ -294,7 +294,7 @@
 
 // Composition of two loss functions.  The error is the result of first
 // evaluating g followed by f to yield the composition f(g(s)).
-// The loss functions must not be NULL.
+// The loss functions must not be nullptr.
 class CERES_EXPORT ComposedLoss : public LossFunction {
  public:
   explicit ComposedLoss(const LossFunction* f,
@@ -322,8 +322,8 @@
 // s -> a * rho'(s)
 // s -> a * rho''(s)
 //
-// Since we treat the a NULL Loss function as the Identity loss
-// function, rho = NULL is a valid input and will result in the input
+// Since we treat the a nullptr Loss function as the Identity loss
+// function, rho = nullptr is a valid input and will result in the input
 // being scaled by a. This provides a simple way of implementing a
 // scaled ResidualBlock.
 class CERES_EXPORT ScaledLoss : public LossFunction {
@@ -361,8 +361,8 @@
 // whose scale can be mutated after an optimization problem has been
 // constructed.
 //
-// Since we treat the a NULL Loss function as the Identity loss
-// function, rho = NULL is a valid input.
+// Since we treat the a nullptr Loss function as the Identity loss
+// function, rho = nullptr is a valid input.
 //
 // Example usage
 //
@@ -403,7 +403,7 @@
   }
 
   void Evaluate(double sq_norm, double out[3]) const override {
-    if (rho_.get() == NULL) {
+    if (rho_.get() == nullptr) {
       out[0] = sq_norm;
       out[1] = 1.0;
       out[2] = 0.0;
diff --git a/include/ceres/numeric_diff_cost_function.h b/include/ceres/numeric_diff_cost_function.h
index 43fe768..f147b16 100644
--- a/include/ceres/numeric_diff_cost_function.h
+++ b/include/ceres/numeric_diff_cost_function.h
@@ -219,7 +219,7 @@
       return false;
     }
 
-    if (jacobians == NULL) {
+    if (jacobians == nullptr) {
       return true;
     }
 
diff --git a/include/ceres/solver.h b/include/ceres/solver.h
index eac6134..fb362be 100644
--- a/include/ceres/solver.h
+++ b/include/ceres/solver.h
@@ -423,7 +423,7 @@
     // each group, Ceres is free to order the parameter blocks as it
     // chooses.
     //
-    // If NULL, then all parameter blocks are assumed to be in the
+    // If nullptr, then all parameter blocks are assumed to be in the
     // same group and the solver is free to decide the best
     // ordering.
     //
diff --git a/include/ceres/tiny_solver_autodiff_function.h b/include/ceres/tiny_solver_autodiff_function.h
index b782f54..59ede83 100644
--- a/include/ceres/tiny_solver_autodiff_function.h
+++ b/include/ceres/tiny_solver_autodiff_function.h
@@ -127,7 +127,7 @@
   // This is similar to AutoDifferentiate(), but since there is only one
   // parameter block it is easier to inline to avoid overhead.
   bool operator()(const T* parameters, T* residuals, T* jacobian) const {
-    if (jacobian == NULL) {
+    if (jacobian == nullptr) {
       // No jacobian requested, so just directly call the cost function with
       // doubles, skipping jets and derivatives.
       return cost_functor_(parameters, residuals);
diff --git a/include/ceres/tiny_solver_cost_function_adapter.h b/include/ceres/tiny_solver_cost_function_adapter.h
index 18ccb39..8ceb7aa 100644
--- a/include/ceres/tiny_solver_cost_function_adapter.h
+++ b/include/ceres/tiny_solver_cost_function_adapter.h
@@ -108,7 +108,7 @@
                   double* residuals,
                   double* jacobian) const {
     if (!jacobian) {
-      return cost_function_.Evaluate(&parameters, residuals, NULL);
+      return cost_function_.Evaluate(&parameters, residuals, nullptr);
     }
 
     double* jacobians[1] = {row_major_jacobian_.data()};
diff --git a/internal/ceres/miniglog/glog/logging.h b/internal/ceres/miniglog/glog/logging.h
index 67ca18a..8f95e09 100644
--- a/internal/ceres/miniglog/glog/logging.h
+++ b/internal/ceres/miniglog/glog/logging.h
@@ -69,7 +69,7 @@
 // The following CHECK macros are defined:
 //
 //   CHECK(condition)        - fails if condition is false and logs condition.
-//   CHECK_NOTNULL(variable) - fails if the variable is NULL.
+//   CHECK_NOTNULL(variable) - fails if the variable is nullptr.
 //
 // The following binary check macros are also defined :
 //
@@ -406,7 +406,7 @@
 // and smart pointers.
 template <typename T>
 T& CheckNotNullCommon(const char* file, int line, const char* names, T& t) {
-  if (t == NULL) {
+  if (t == nullptr) {
     LogMessageFatal(file, line, std::string(names));
   }
   return t;
@@ -424,17 +424,17 @@
 
 // Check that a pointer is not null.
 #define CHECK_NOTNULL(val) \
-  CheckNotNull(__FILE__, __LINE__, "'" #val "' Must be non NULL", (val))
+  CheckNotNull(__FILE__, __LINE__, "'" #val "' Must be non nullptr", (val))
 
 #ifndef NDEBUG
 // Debug only version of CHECK_NOTNULL
 #define DCHECK_NOTNULL(val) \
-  CheckNotNull(__FILE__, __LINE__, "'" #val "' Must be non NULL", (val))
+  CheckNotNull(__FILE__, __LINE__, "'" #val "' Must be non nullptr", (val))
 #else
 // Optimized version - generates no code.
 #define DCHECK_NOTNULL(val) \
   if (false)                \
-  CheckNotNull(__FILE__, __LINE__, "'" #val "' Must be non NULL", (val))
+  CheckNotNull(__FILE__, __LINE__, "'" #val "' Must be non nullptr", (val))
 #endif  // NDEBUG
 
 #include "ceres/internal/reenable_warnings.h"