diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index be9028d38c..0a0ebc1598 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -1153,11 +1153,13 @@ static int reserve_offlined_page(struct page_info *head)
 
         next_order = cur_order = 0;
 
+        /* Attempt to grow the order (size) of the buddy as much as possible. */
         while ( cur_order < head_order )
         {
             next_order = cur_order + 1;
 
-            if ( (cur_head + (1 << next_order)) >= (head + ( 1 << head_order)) )
+            /* Do not grow to next_order if it would go beyond the buddy. */
+            if ( (cur_head + (1 << next_order)) > (head + (1 << head_order)) )
                 goto merge;
 
             /* Do not grow to next_order if cur_head is not aligned to it. */