diff --git a/internal/ceres/problem_impl.cc b/internal/ceres/problem_impl.cc
index 7c86efb..67cac94 100644
--- a/internal/ceres/problem_impl.cc
+++ b/internal/ceres/problem_impl.cc
@@ -823,6 +823,16 @@
   }
 }
 
+const CostFunction* ProblemImpl::GetCostFunctionForResidualBlock(
+    const ResidualBlockId residual_block) const {
+  return residual_block->cost_function();
+}
+
+const LossFunction* ProblemImpl::GetLossFunctionForResidualBlock(
+    const ResidualBlockId residual_block) const {
+  return residual_block->loss_function();
+}
+
 void ProblemImpl::GetResidualBlocksForParameterBlock(
     const double* values,
     vector<ResidualBlockId>* residual_blocks) const {