diff --git a/internal/ceres/visibility.h b/internal/ceres/visibility.h
index 115d45f..68c6723 100644
--- a/internal/ceres/visibility.h
+++ b/internal/ceres/visibility.h
@@ -37,7 +37,9 @@
 
 #include <set>
 #include <vector>
+
 #include "ceres/graph.h"
+#include "ceres/internal/port.h"
 
 namespace ceres {
 namespace internal {
@@ -52,9 +54,10 @@
 //
 // In a structure from motion problem, e_blocks correspond to 3D
 // points and f_blocks correspond to cameras.
-void ComputeVisibility(const CompressedRowBlockStructure& block_structure,
-                       int num_eliminate_blocks,
-                       std::vector<std::set<int>>* visibility);
+CERES_EXPORT_INTERNAL void ComputeVisibility(
+    const CompressedRowBlockStructure& block_structure,
+    int num_eliminate_blocks,
+    std::vector<std::set<int>>* visibility);
 
 // Given f_block visibility as computed by the ComputeVisibility
 // function above, construct and return a graph whose vertices are
@@ -69,7 +72,7 @@
 //
 // Caller acquires ownership of the returned WeightedGraph pointer
 // (heap-allocated).
-WeightedGraph<int>* CreateSchurComplementGraph(
+CERES_EXPORT_INTERNAL WeightedGraph<int>* CreateSchurComplementGraph(
     const std::vector<std::set<int>>& visibility);
 
 }  // namespace internal