diff --git a/internal/ceres/residual_block_test.cc b/internal/ceres/residual_block_test.cc
index b37f50f..22873e7 100644
--- a/internal/ceres/residual_block_test.cc
+++ b/internal/ceres/residual_block_test.cc
@@ -39,6 +39,8 @@
 namespace ceres {
 namespace internal {
 
+using std::vector;
+
 // Trivial cost function that accepts three arguments.
 class TernaryCostFunction: public CostFunction {
  public: