diff --git a/include/my_tree.h b/include/my_tree.h
index 7cc7c615ba6..6aec50215ca 100644
--- a/include/my_tree.h
+++ b/include/my_tree.h
@@ -20,7 +20,9 @@
 extern "C" {
 #endif
 
-#define MAX_TREE_HIGHT	40	/* = max 1048576 leafs in tree */
+/* Worst case tree is half full. This gives use 2^(MAX_TREE_HIGHT/2) leafs */
+#define MAX_TREE_HIGHT	64
+
 #define ELEMENT_KEY(tree,element)\
 (tree->offset_to_key ? (void*)((byte*) element+tree->offset_to_key) :\
 			*((void**) (element+1)))