diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,10 @@
 and this project adheres to the
 [Haskell Package Versioning Policy](https://pvp.haskell.org/).
 
+## 0.4.0.2 - 2023-09-05
+
+- Flush interval cannot be zero or below.
+
 ## 0.4.0.1 - 2023-09-05
 
 - Improve resilience against bad input.
diff --git a/src/System/Metrics/StatsD/Internal.hs b/src/System/Metrics/StatsD/Internal.hs
--- a/src/System/Metrics/StatsD/Internal.hs
+++ b/src/System/Metrics/StatsD/Internal.hs
@@ -280,7 +280,7 @@
     v =
       all validateKey [bs, bg, bc, bt, be]
         && bool (validateKey bn) True (null cfg.namespace)
-        && 0 <= cfg.flushInterval
+        && cfg.flushInterval > 0
         && all (\pc -> pc > 0 && 100 > pc) cfg.timingPercentiles
     pfx =
       if null cfg.namespace
diff --git a/statsd-rupp.cabal b/statsd-rupp.cabal
--- a/statsd-rupp.cabal
+++ b/statsd-rupp.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           statsd-rupp
-version:        0.4.0.1
+version:        0.4.0.2
 synopsis:       Simple StatsD Client
 description:    Please see the README on GitHub at <https://github.com/jprupp/statsd-rupp#readme>
 category:       System