diff --git a/src/pvec/containers_pvec.ml b/src/pvec/containers_pvec.ml
index c0c0eee2..d4c7f502 100644
--- a/src/pvec/containers_pvec.ml
+++ b/src/pvec/containers_pvec.ml
@@ -4,7 +4,7 @@
 
 type 'a iter = ('a -> unit) -> unit
 
-let num_bits = 5
+let num_bits = 4
 let branching_factor = 1 lsl num_bits
 let bitmask = branching_factor - 1