diff --git a/constraints.txt b/constraints.txt
index 3ece2ede07..3139e0397c 100644
--- a/constraints.txt
+++ b/constraints.txt
@@ -20,7 +20,7 @@ WebTest==2.0.33
 ZConfig==3.4.0
 ZEO==5.2.1
 ZODB==5.5.1
-ZServer==4.0 ; python_version < '3.0'
+ZServer==4.0.1 ; python_version < '3.0'
 Zope2==4.0b1
 five.globalrequest==99.1
 five.localsitemanager==3.2.2
diff --git a/versions-prod.cfg b/versions-prod.cfg
index 6fc3cda548..1b2d3fd6af 100644
--- a/versions-prod.cfg
+++ b/versions-prod.cfg
@@ -26,7 +26,7 @@ WebTest = 2.0.33
 ZConfig = 3.4.0
 ZEO = 5.2.1
 ZODB = 5.5.1
-ZServer = 4.0
+ZServer = 4.0.1
 five.globalrequest = 99.1
 five.localsitemanager = 3.2.2
 funcsigs = 1.0.2