diff --git a/internal/ceres/array_utils.h b/internal/ceres/array_utils.h
index 1d55733..68feca5 100644
--- a/internal/ceres/array_utils.h
+++ b/internal/ceres/array_utils.h
@@ -44,6 +44,7 @@
 #define CERES_INTERNAL_ARRAY_UTILS_H_
 
 #include <string>
+
 #include "ceres/internal/port.h"
 
 namespace ceres {
@@ -51,20 +52,22 @@
 
 // Fill the array x with an impossible value that the user code is
 // never expected to compute.
-void InvalidateArray(int size, double* x);
+CERES_EXPORT_INTERNAL void InvalidateArray(int size, double* x);
 
 // Check if all the entries of the array x are valid, i.e. all the
 // values in the array should be finite and none of them should be
 // equal to the "impossible" value used by InvalidateArray.
-bool IsArrayValid(int size, const double* x);
+CERES_EXPORT_INTERNAL bool IsArrayValid(int size, const double* x);
 
 // If the array contains an invalid value, return the index for it,
 // otherwise return size.
-int FindInvalidValue(const int size, const double* x);
+CERES_EXPORT_INTERNAL int FindInvalidValue(const int size, const double* x);
 
 // Utility routine to print an array of doubles to a string. If the
 // array pointer is NULL, it is treated as an array of zeros.
-void AppendArrayToString(const int size, const double* x, std::string* result);
+CERES_EXPORT_INTERNAL void AppendArrayToString(const int size,
+                                               const double* x,
+                                               std::string* result);
 
 // This routine takes an array of integer values, sorts and uniques
 // them and then maps each value in the array to its position in the
@@ -79,7 +82,7 @@
 // gets mapped to
 //
 // [1 0 2 3 0 1 3]
-void MapValuesToContiguousRange(int size, int* array);
+CERES_EXPORT_INTERNAL void MapValuesToContiguousRange(int size, int* array);
 
 }  // namespace internal
 }  // namespace ceres