diff --git a/include/ceres/cost_function.h b/include/ceres/cost_function.h
index 722ac77..fee3e73 100644
--- a/include/ceres/cost_function.h
+++ b/include/ceres/cost_function.h
@@ -60,7 +60,7 @@
 // code inheriting from this class is expected to set these two members with the
 // corresponding accessors. This information will be verified by the Problem
 // when added with AddResidualBlock().
-class CostFunction {
+class CERES_EXPORT CostFunction {
  public:
   CostFunction() : num_residuals_(0) {}