diff --git a/include/ceres/solver.h b/include/ceres/solver.h
index 390bb0adf..10499592f 100644
--- a/include/ceres/solver.h
+++ b/include/ceres/solver.h
@@ -717,7 +717,7 @@ class Solver {
     LineSearchDirectionType line_search_direction_type;
     LineSearchType line_search_type;
     LineSearchInterpolationType line_search_interpolation_type;
-    NonlinearConjugateGradient nonlinear_conjugate_gradient_type;
+    NonlinearConjugateGradientType nonlinear_conjugate_gradient_type;
 
     int max_lbfgs_rank;
   };