diff --git a/internal/ceres/lapack.h b/internal/ceres/lapack.h
index 5bb1a22..5c5bf8b 100644
--- a/internal/ceres/lapack.h
+++ b/internal/ceres/lapack.h
@@ -32,6 +32,7 @@
 #define CERES_INTERNAL_LAPACK_H_
 
 #include <string>
+
 #include "ceres/internal/port.h"
 #include "ceres/linear_solver.h"