diff --git a/docs/source/nnls_modeling.rst b/docs/source/nnls_modeling.rst
index dc43398..388ccfd 100644
--- a/docs/source/nnls_modeling.rst
+++ b/docs/source/nnls_modeling.rst
@@ -380,7 +380,7 @@
       template <typename CostFunctor,
                 NumericDiffMethodType method = CENTRAL,
                 int kNumResiduals,  // Number of residuals, or ceres::DYNAMIC.
-                int... Ns>           // Size of each parameter block.
+                int... Ns>          // Size of each parameter block.
       class NumericDiffCostFunction : public
       SizedCostFunction<kNumResiduals, Ns> {
       };