diff --git a/main/src/main/scala/sbt/internal/LintUnused.scala b/main/src/main/scala/sbt/internal/LintUnused.scala
index 3eb0a7398..d29993b18 100644
--- a/main/src/main/scala/sbt/internal/LintUnused.scala
+++ b/main/src/main/scala/sbt/internal/LintUnused.scala
@@ -38,6 +38,7 @@ object LintUnused {
       onUnload,
       sbt.nio.Keys.watchTriggers,
       serverConnectionType,
+      serverIdleTimeout,
       shellPrompt,
     ),
     includeLintKeys := Set(