diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 2893f3b..a60d0fd 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -11,6 +11,7 @@
 #ifndef XLOG_H
 #define XLOG_H
 
+#include "c.h"
 #include "access/rmgr.h"
 #include "access/xlogdefs.h"
 #include "datatype/timestamp.h"
diff --git a/src/include/utils/timestamp.h b/src/include/utils/timestamp.h
index e7cdb41..bd2fd17 100644
--- a/src/include/utils/timestamp.h
+++ b/src/include/utils/timestamp.h
@@ -13,6 +13,7 @@
 #ifndef TIMESTAMP_H
 #define TIMESTAMP_H
 
+#include "c.h"
 #include "datatype/timestamp.h"
 #include "fmgr.h"
 #include "pgtime.h"