diff --git a/src/include/storage/md.h b/src/include/storage/md.h
index 87a00516278bb..3c9b966bffc96 100644
--- a/src/include/storage/md.h
+++ b/src/include/storage/md.h
@@ -21,7 +21,7 @@
 
 /* registration function for md storage manager */
 extern void mdsmgr_register(void);
-extern SMgrId MdSMgrId;
+extern PGDLLIMPORT SMgrId MdSMgrId;
 
 /* md storage manager functionality */
 extern void mdinit(void);