diff --git a/src/include/storage/smgr.h b/src/include/storage/smgr.h
index 19e469e1cef..43fee9e052c 100644
--- a/src/include/storage/smgr.h
+++ b/src/include/storage/smgr.h
@@ -20,6 +20,12 @@
 
 struct f_smgr;
 
+/*
+ * Neon: extended SMGR API.
+ * This define can be used by extensions to determine that them are built for Neon.
+ */
+#define NEON_SMGR 1
+
 /*
  * smgr.c maintains a table of SMgrRelation objects, which are essentially
  * cached file handles.  An SMgrRelation is created (if not already present)