diff --git a/src/backend/nodes/tidbitmap.c b/src/backend/nodes/tidbitmap.c
index 3ef0112..43628ac 100644
--- a/src/backend/nodes/tidbitmap.c
+++ b/src/backend/nodes/tidbitmap.c
@@ -361,7 +361,7 @@ tbm_union_page(TIDBitmap *a, const PagetableEntry *bpage)
        if (bpage->ischunk)
        {
                /* Scan b's chunk, mark each indicated page lossy in a */
-               for (wordnum = 0; wordnum < WORDS_PER_PAGE; wordnum++)
+               for (wordnum = 0; wordnum < WORDS_PER_CHUNK; wordnum++)
                {
                        bitmapword      w = bpage->words[wordnum];

@@ -473,7 +473,7 @@ tbm_intersect_page(TIDBitmap *a, PagetableEntry *apage, const TIDBitmap *b)
                /* Scan each bit in chunk, try to clear */
                bool            candelete = true;

-               for (wordnum = 0; wordnum < WORDS_PER_PAGE; wordnum++)
+               for (wordnum = 0; wordnum < WORDS_PER_CHUNK; wordnum++)
                {
                        bitmapword      w = apage->words[wordnum];