diff --git a/src/buffer.cc b/src/buffer.cc
index 04c53083..07383257 100644
--- a/src/buffer.cc
+++ b/src/buffer.cc
@@ -8,6 +8,7 @@
 #include "diff.hh"
 #include "file.hh"
 #include "flags.hh"
+#include "option_types.hh"
 #include "shared_string.hh"
 #include "unit_tests.hh"
 #include "utils.hh"