diff --git a/dependency-tree/src/main/scala/sbt/plugins/DependencyTreePlugin.scala b/dependency-tree/src/main/scala/sbt/plugins/DependencyTreePlugin.scala
index a1e93a3aa..9a6866703 100644
--- a/dependency-tree/src/main/scala/sbt/plugins/DependencyTreePlugin.scala
+++ b/dependency-tree/src/main/scala/sbt/plugins/DependencyTreePlugin.scala
@@ -20,11 +20,11 @@ object DependencyTreePlugin extends AutoPlugin {
   val configurations = Vector(Compile, Test, IntegrationTest, Runtime, Provided, Optional)
 
   // MiniDependencyTreePlugin provides baseBasicReportingSettings for Compile and Test
-  override def projectSettings: Seq[Def.Setting[?]] =
-    ((configurations diff Vector(Compile, Test)) flatMap { config =>
+  override lazy val projectSettings: Seq[Def.Setting[?]] =
+    configurations.diff(Vector(Compile, Test)).flatMap { config =>
       inConfig(config)(DependencyTreeSettings.baseBasicReportingSettings)
-    }) ++
-      (configurations flatMap { config =>
+    } ++
+      configurations.flatMap { config =>
         inConfig(config)(DependencyTreeSettings.baseFullReportingSettings)
-      })
+      }
 }
diff --git a/main/src/main/scala/sbt/plugins/MiniDependencyTreePlugin.scala b/main/src/main/scala/sbt/plugins/MiniDependencyTreePlugin.scala
index c042cec10..aba6da778 100644
--- a/main/src/main/scala/sbt/plugins/MiniDependencyTreePlugin.scala
+++ b/main/src/main/scala/sbt/plugins/MiniDependencyTreePlugin.scala
@@ -21,7 +21,7 @@ object MiniDependencyTreePlugin extends AutoPlugin {
   override def globalSettings: Seq[Def.Setting[?]] = Seq(
     dependencyTreeIncludeScalaLibrary := false
   )
-  override def projectSettings: Seq[Def.Setting[?]] =
+  override lazy val projectSettings: Seq[Def.Setting[?]] =
     DependencyTreeSettings.coreSettings ++
       inConfig(Compile)(DependencyTreeSettings.baseBasicReportingSettings) ++
       inConfig(Test)(DependencyTreeSettings.baseBasicReportingSettings)