diff --git a/pgxn/neon/libpagestore.c b/pgxn/neon/libpagestore.c
index 07a19a7114..6c6489277d 100644
--- a/pgxn/neon/libpagestore.c
+++ b/pgxn/neon/libpagestore.c
@@ -937,7 +937,7 @@ PagestoreShmemInit(void)
 
 	LWLockAcquire(AddinShmemInitLock, LW_EXCLUSIVE);
 	pagestore_shared = ShmemInitStruct("libpagestore shared state",
-									   PagestoreShmemSize(),
+									   sizeof(PagestoreShmemState),
 									   &found);
 	if (!found)
 	{