diff --git a/main/Project.scala b/main/Project.scala
index 36ce12f8c..bfe528295 100644
--- a/main/Project.scala
+++ b/main/Project.scala
@@ -137,6 +137,7 @@ object Project extends Init[Scope] with ProjectExtra
 
 	def setProject(session: SessionSettings, structure: BuildStructure, s: State): State =
 	{
+		SessionSettings.checkSession(session, s)
 		val previousOnUnload = orIdentity(s get Keys.onUnload.key)
 		val unloaded = previousOnUnload(s.runExitHooks())
 		val (onLoad, onUnload) = getHooks(structure.data)
diff --git a/main/SessionSettings.scala b/main/SessionSettings.scala
index 3b9b4835f..cc8a7a86e 100644
--- a/main/SessionSettings.scala
+++ b/main/SessionSettings.scala
@@ -53,7 +53,14 @@ object SessionSettings
 		else
 			f(session)
 	}
-	
+
+	def pluralize(size: Int, of: String) = size.toString + (if(size == 1) of else (of + "s"))
+	def checkSession(newSession: SessionSettings, oldState: State)
+	{
+		val oldSettings = (oldState get Keys.sessionSettings).toList.flatMap(_.append).flatMap(_._2)
+		if(newSession.append.isEmpty && !oldSettings.isEmpty)
+			logger(oldState).warn("Discarding " + pluralize(oldSettings.size, " session setting") + ".  Use 'session save' to persist session settings.")
+	}
 	def removeRanges[T](in: Seq[T], ranges: Seq[(Int,Int)]): Seq[T] =
 	{
 		val asSet = (Set.empty[Int] /: ranges) { case (s, (hi,lo)) => s ++ (hi to lo) }