diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index 77e301b7c63..8b5571374d0 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -3118,7 +3118,7 @@ restore_tuple(BufFile *file, Relation relation, MemoryContext cxt)
 	BufFileReadExact(file, &natt_ext, sizeof(natt_ext));
 	for (int i = 0; i < natt_ext; i++)
 	{
-		varlena		varhdr;
+		alignas(uint32) varlena		varhdr;
 		char	   *ext_val;
 		Size		ext_val_size;