diff --git a/webserver/plugin.jelly b/webserver/plugin.jelly
index 4210a8a2..5e3ffe48 100644
--- a/webserver/plugin.jelly
+++ b/webserver/plugin.jelly
@@ -148,6 +148,22 @@
       <exception:requiredPropertyMissing propname="maven.webserver.root" />
     </j:if>
 
+    <!-- sanity check for preset variables -->
+    <j:choose>
+      <j:when test="${context.getVariable('maven.webserver.port.http') == null}">
+        <j:if test="${context.getVariable('maven.webserver.port.https') == null}">
+          <exception:requiredPropertyMissing
+            propname="maven.webserver.port.http OR maven.webserver.port.https" />
+        </j:if>
+      </j:when>
+      <j:when test="${context.getVariable('maven.webserver.port.https') == null}">
+        <j:if test="${context.getVariable('maven.webserver.port.http') == null}">
+          <exception:requiredPropertyMissing
+            propname="maven.webserver.port.http OR maven.webserver.port.https" />
+        </j:if>
+      </j:when>
+    </j:choose>
+
     <!-- These are special cases where the user should not override -->
     <j:if test="${context.getVariable('maven.webserver.fullname') == null}">
       <exception:requiredPropertyMissing propname="maven.webserver.fullname" />
@@ -183,12 +199,12 @@
         value="${maven.webserver.port.http}" />
       <ant:filter token="maven.webserver.port.https"
         value="${maven.webserver.port.https}" />
-      <ant:filter token="maven.webserver.port.one"
-        value="${maven.webserver.port.one}" />
-      <ant:filter token="maven.webserver.port.two"
-        value="${maven.webserver.port.two}" />
-      <ant:filter token="maven.webserver.port.three"
-        value="${maven.webserver.port.three}" />
+      <ant:filter token="maven.webserver.port.A"
+        value="${maven.webserver.port.A}" />
+      <ant:filter token="maven.webserver.port.B"
+        value="${maven.webserver.port.B}" />
+      <ant:filter token="maven.webserver.port.C"
+        value="${maven.webserver.port.C}" />
       <ant:filter token="maven.webserver.conf.dir"
         value="${maven.webserver.conf.dir.path}" />
       <ant:filter token="maven.webserver.host"
@@ -247,7 +263,7 @@ Maven has determined your <j:expr value="${maven.webserver.fullname}"/> webserve
 
     <j:if test="${context.getVariable('maven.webserver.test.url') == null}">
     <log:info trim="false">
-Maven has determined your <j:expr value="${maven.webserver.fullname}"/> webserver instance is <j:expr value="${maven.webserver.installed.msg}"/> in directory [ <j:expr value="${maven.webserver.dir}"/> ] and <j:expr value="${maven.webserver.started.msg}"/> using socket <j:expr value="${maven.webserver.port.http}"/> on host <j:expr value="${maven.webserver.host}"/>.
+Maven has determined your <j:expr value="${maven.webserver.fullname}"/> webserver instance is <j:expr value="${maven.webserver.installed.msg}"/> in directory [ <j:expr value="${maven.webserver.dir}"/> ] and <j:expr value="${maven.webserver.started.msg}"/> using socket <j:expr value="${maven.webserver.test.socket}"/> on host <j:expr value="${maven.webserver.host}"/>.
     </log:info>
     </j:if>