diff --git a/src/libraries/OS-Independent/Data/Set.icl b/src/libraries/OS-Independent/Data/Set.icl
index c70917e8972bfa2197546f59a31d464d81006dc4..6a692fc4306884ddc15ada19be150cd144a008bc 100644
--- a/src/libraries/OS-Independent/Data/Set.icl
+++ b/src/libraries/OS-Independent/Data/Set.icl
@@ -454,7 +454,7 @@ maxView x = Just (deleteFindMax x)
   However (since we use quickcheck :-) we will stick to strictly balanced 
   trees.
 --------------------------------------------------------------------*/
-delta :== 4
+delta :== 3
 ratio :== 2
 
 // Functions balanceL and balanceR are specialised versions of balance.