diff --git a/build.sbt b/build.sbt
index 2f2cb6553..2a16a7065 100644
--- a/build.sbt
+++ b/build.sbt
@@ -391,6 +391,8 @@ lazy val mainProj = (project in file("main"))
       exclude[DirectMissingMethodProblem]("sbt.internal.KeyIndex.*"),
       // Removed unused val. internal.
       exclude[DirectMissingMethodProblem]("sbt.internal.RelayAppender.jsonFormat"),
+      // Removed unused def. internal.
+      exclude[DirectMissingMethodProblem]("sbt.internal.Load.isProjectThis"),
     )
   )
   .configure(
diff --git a/main-settings/src/main/scala/sbt/Scope.scala b/main-settings/src/main/scala/sbt/Scope.scala
index edfeb4826..34815405a 100644
--- a/main-settings/src/main/scala/sbt/Scope.scala
+++ b/main-settings/src/main/scala/sbt/Scope.scala
@@ -97,8 +97,7 @@ object Scope {
       case LocalProject(id)    => ProjectRef(current, id)
       case RootProject(uri)    => RootProject(resolveBuild(current, uri))
       case ProjectRef(uri, id) => ProjectRef(resolveBuild(current, uri), id)
-      case ThisProject =>
-        RootProject(current) // Is this right? It was an inexhaustive match before..
+      case ThisProject         => ThisProject // haven't exactly "resolved" anything..
     }
   def resolveBuild(current: URI, uri: URI): URI =
     if (!uri.isAbsolute && current.isOpaque && uri.getSchemeSpecificPart == ".")
@@ -118,13 +117,11 @@ object Scope {
                         rootProject: URI => String,
                         ref: ProjectReference): ProjectRef =
     ref match {
-      case LocalRootProject => ProjectRef(current, rootProject(current))
-      case LocalProject(id) => ProjectRef(current, id)
-      case RootProject(uri) =>
-        val res = resolveBuild(current, uri); ProjectRef(res, rootProject(res))
+      case LocalRootProject    => ProjectRef(current, rootProject(current))
+      case LocalProject(id)    => ProjectRef(current, id)
+      case RootProject(uri)    => val u = resolveBuild(current, uri); ProjectRef(u, rootProject(u))
       case ProjectRef(uri, id) => ProjectRef(resolveBuild(current, uri), id)
-      case ThisProject =>
-        ProjectRef(current, rootProject(current)) // Is this right? It was an inexhaustive match before..
+      case ThisProject         => sys.error("Cannot resolve ThisProject w/o the current project")
     }
   def resolveBuildRef(current: URI, ref: BuildReference): BuildRef =
     ref match {
diff --git a/main/src/main/scala/sbt/internal/Load.scala b/main/src/main/scala/sbt/internal/Load.scala
index e0ac0b6f8..b10235eac 100755
--- a/main/src/main/scala/sbt/internal/Load.scala
+++ b/main/src/main/scala/sbt/internal/Load.scala
@@ -363,12 +363,6 @@ private[sbt] object Load {
     )
   }
 
-  def isProjectThis(s: Setting[_]): Boolean =
-    s.key.scope.project match {
-      case This | Select(ThisProject) => true
-      case _                          => false
-    }
-
   def buildConfigurations(
       loaded: LoadedBuild,
       rootProject: URI => String,