Add forgotten header.

1 files changed, 1 insertions, 0 deletions

diff --git a/boundary.c b/boundary.c
index c0f1514..86803fc 100644
--- a/boundary.c
+++ b/boundary.c
@@ -21,6 +21,7 @@
 
 #include "common.h"
 #include "mg2d_boundary.h"
+#include "mg2d_boundary_internal.h"
 
 struct MG2DBoundaryInternal {
     double *val_base;