diff --git a/include/ceres/cost_function_to_functor.h b/include/ceres/cost_function_to_functor.h
index 0d01f77..b4a516e 100644
--- a/include/ceres/cost_function_to_functor.h
+++ b/include/ceres/cost_function_to_functor.h
@@ -107,9 +107,7 @@
   explicit CostFunctionToFunctor(CostFunction* cost_function)
   : cost_function_(cost_function) {
     CHECK_NOTNULL(cost_function);
-
-    CHECK_GE(kNumResiduals, 0);
-    CHECK_EQ(cost_function->num_residuals(), kNumResiduals);
+    CHECK(kNumResiduals > 0 || kNumResiduals == DYNAMIC);
 
     // This block breaks the 80 column rule to keep it somewhat readable.
     CHECK((!N1 && !N2 && !N3 && !N4 && !N5 && !N6 && !N7 && !N8 && !N9) ||
diff --git a/internal/ceres/cost_function_to_functor_test.cc b/internal/ceres/cost_function_to_functor_test.cc
index fd828ce..f758efe 100644
--- a/internal/ceres/cost_function_to_functor_test.cc
+++ b/internal/ceres/cost_function_to_functor_test.cc
@@ -300,6 +300,19 @@
 
 #undef TEST_BODY
 
+TEST(CostFunctionToFunctor, DynamicNumberOfResiduals) {
+  scoped_ptr<CostFunction> cost_function(
+      new AutoDiffCostFunction<
+      CostFunctionToFunctor<ceres::DYNAMIC, 2, 2 >, ceres::DYNAMIC, 2, 2>(
+          new CostFunctionToFunctor<ceres::DYNAMIC, 2, 2 >(
+              new AutoDiffCostFunction<TwoParameterBlockFunctor, 2, 2, 2 >(
+                  new TwoParameterBlockFunctor)), 2));
+
+  scoped_ptr<CostFunction> actual_cost_function(
+      new AutoDiffCostFunction<TwoParameterBlockFunctor, 2, 2, 2 >(
+          new TwoParameterBlockFunctor));
+  ExpectCostFunctionsAreEqual(*cost_function, *actual_cost_function);
+}
 
 }  // namespace internal
 }  // namespace ceres