diff --git a/doc/buckets.qbk b/doc/buckets.qbk
index 24778aaa..7dba891d 100644
--- a/doc/buckets.qbk
+++ b/doc/buckets.qbk
@@ -97,9 +97,10 @@ elements into container `x`, you could first call:
     x.rehash((x.size() + n) / x.max_load_factor() + 1);
 
 [blurb Note: `rehash`'s argument is the number of buckets, not the number of
-elements, which is why the new size is divided by the maximum load factor. The
-`+ 1` is required because the container is allowed to resize when the load
-factor is equal to the maximum load factor.]
+elements, which is why the new size is divided by the maximum load factor.  The
++ 1 guarantees there is no invalidation; without it, reallocation could occur
+if the number of bucket exactly divides the target size, since the container is
+allowed to rehash when the load factor is equal to the maximum load factor.]
 
 [table Methods for Controlling Bucket Size
     [[Method] [Description]]