diff --git a/src/hnswinsert.c b/src/hnswinsert.c
index 04a10f9..27562a9 100644
--- a/src/hnswinsert.c
+++ b/src/hnswinsert.c
@@ -78,6 +78,10 @@ HnswFreeOffset(Relation index, Buffer buf, Page page, HnswElement element, Size
 
 			nitemid = PageGetItemId(*npage, neighborOffno);
 
+			/* Ensure aligned for space check */
+			Assert(etupSize == MAXALIGN(etupSize));
+			Assert(ntupSize == MAXALIGN(ntupSize));
+
 			/*
 			 * Calculate free space individually since tuples are overwritten
 			 * individually (in separate calls to PageIndexTupleOverwrite)