diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h
index be3add95dca..9758835e4d6 100644
--- a/src/include/miscadmin.h
+++ b/src/include/miscadmin.h
@@ -199,8 +199,8 @@ extern PGDLLIMPORT Oid MyDatabaseTableSpace;
 #define DATEORDER_DMY			1
 #define DATEORDER_MDY			2
 
-extern int	DateStyle;
-extern int	DateOrder;
+extern PGDLLIMPORT int DateStyle;
+extern PGDLLIMPORT int DateOrder;
 
 /*
  * IntervalStyles
@@ -214,7 +214,7 @@ extern int	DateOrder;
 #define INTSTYLE_SQL_STANDARD		2
 #define INTSTYLE_ISO_8601			3
 
-extern int	IntervalStyle;
+extern PGDLLIMPORT int IntervalStyle;
 
 /*
  * HasCTZSet is true if user has set timezone as a numeric offset from UTC.