diff --git a/src/include/storage/page/b_plus_tree_internal_page.h b/src/include/storage/page/b_plus_tree_internal_page.h
index c26a5a86a..dab4222cd 100644
--- a/src/include/storage/page/b_plus_tree_internal_page.h
+++ b/src/include/storage/page/b_plus_tree_internal_page.h
@@ -19,7 +19,7 @@ namespace bustub {
 
 #define B_PLUS_TREE_INTERNAL_PAGE_TYPE BPlusTreeInternalPage<KeyType, ValueType, KeyComparator>
 #define INTERNAL_PAGE_HEADER_SIZE 12
-#define INTERNAL_PAGE_SIZE ((BUSTUB_PAGE_SIZE - INTERNAL_PAGE_HEADER_SIZE) / (sizeof(MappingType)))
+#define INTERNAL_PAGE_SIZE ((BUSTUB_PAGE_SIZE - INTERNAL_PAGE_HEADER_SIZE) / (sizeof(std::pair<KeyType, page_id_t>)))
 /**
  * Store n indexed keys and n+1 child pointers (page_id) within internal page.
  * Pointer PAGE_ID(i) points to a subtree in which all keys K satisfy: