diff --git a/include/ceres/dynamic_numeric_diff_cost_function.h b/include/ceres/dynamic_numeric_diff_cost_function.h
index c2bfb32..2b6e826 100644
--- a/include/ceres/dynamic_numeric_diff_cost_function.h
+++ b/include/ceres/dynamic_numeric_diff_cost_function.h
@@ -104,7 +104,7 @@
         << "You must call DynamicNumericDiffCostFunction::SetNumResiduals() "
         << "before DynamicNumericDiffCostFunction::Evaluate().";
 
-    const vector<int16>& block_sizes = parameter_block_sizes();
+    const vector<int32>& block_sizes = parameter_block_sizes();
     CHECK(!block_sizes.empty())
         << "You must call DynamicNumericDiffCostFunction::AddParameterBlock() "
         << "before DynamicNumericDiffCostFunction::Evaluate().";