diff --git a/src/compiler/scala/tools/nsc/transform/Delambdafy.scala b/src/compiler/scala/tools/nsc/transform/Delambdafy.scala
index d2c511a2d1fd..1f832ba81eab 100644
--- a/src/compiler/scala/tools/nsc/transform/Delambdafy.scala
+++ b/src/compiler/scala/tools/nsc/transform/Delambdafy.scala
@@ -113,7 +113,9 @@ abstract class Delambdafy extends Transform with TypingTransformers with ast.Tre
     // after working on the entire compilation until we'll have a set of
     // new class definitions to add to the top level
     override def transformStats(stats: List[Tree], exprOwner: Symbol): List[Tree] = {
-      super.transformStats(stats, exprOwner) ++ lambdaClassDefs(exprOwner)
+      // Need to remove from the lambdaClassDefs map: there may be multiple PackageDef for the same
+      // package when defining a package object. We only add the lambda class to one. See SI-9097.
+      super.transformStats(stats, exprOwner) ++ lambdaClassDefs.remove(exprOwner).getOrElse(Nil)
     }
 
     private def optionSymbol(sym: Symbol): Option[Symbol] = if (sym.exists) Some(sym) else None
diff --git a/src/compiler/scala/tools/nsc/transform/Flatten.scala b/src/compiler/scala/tools/nsc/transform/Flatten.scala
index 6149e40fa7f7..fbb030777341 100644
--- a/src/compiler/scala/tools/nsc/transform/Flatten.scala
+++ b/src/compiler/scala/tools/nsc/transform/Flatten.scala
@@ -166,7 +166,7 @@ abstract class Flatten extends InfoTransform {
     override def transformStats(stats: List[Tree], exprOwner: Symbol): List[Tree] = {
       val stats1 = super.transformStats(stats, exprOwner)
       if (currentOwner.isPackageClass) {
-        val lifted = liftedDefs(currentOwner).toList
+        val lifted = liftedDefs.remove(currentOwner).toList.flatten
         stats1 ::: lifted
       }
       else stats1
diff --git a/src/compiler/scala/tools/nsc/transform/LambdaLift.scala b/src/compiler/scala/tools/nsc/transform/LambdaLift.scala
index fa0c1f797bc3..a703542587e7 100644
--- a/src/compiler/scala/tools/nsc/transform/LambdaLift.scala
+++ b/src/compiler/scala/tools/nsc/transform/LambdaLift.scala
@@ -539,12 +539,11 @@ abstract class LambdaLift extends InfoTransform {
     override def transformStats(stats: List[Tree], exprOwner: Symbol): List[Tree] = {
       def addLifted(stat: Tree): Tree = stat match {
         case ClassDef(_, _, _, _) =>
-          val lifted = liftedDefs get stat.symbol match {
+          val lifted = liftedDefs remove stat.symbol match {
             case Some(xs) => xs reverseMap addLifted
             case _        => log("unexpectedly no lifted defs for " + stat.symbol) ; Nil
           }
-          try deriveClassDef(stat)(impl => deriveTemplate(impl)(_ ::: lifted))
-          finally liftedDefs -= stat.symbol
+          deriveClassDef(stat)(impl => deriveTemplate(impl)(_ ::: lifted))
 
         case DefDef(_, _, _, _, _, Block(Nil, expr)) if !stat.symbol.isConstructor =>
           deriveDefDef(stat)(_ => expr)
diff --git a/test/files/run/t9097.scala b/test/files/run/t9097.scala
new file mode 100644
index 000000000000..d2bf55fc4481
--- /dev/null
+++ b/test/files/run/t9097.scala
@@ -0,0 +1,34 @@
+import scala.tools.partest._
+import java.io.{Console => _, _}
+
+object Test extends StoreReporterDirectTest {
+
+  override def extraSettings: String = List(
+    "-usejavacp",
+    "-Xfatal-warnings",
+    "-Ybackend:GenBCode",
+    "-Ydelambdafy:method",
+    "-Xprint:delambdafy",
+    s"-d ${testOutput.path}"
+  ) mkString " "
+
+  override def code = """package o
+                        |package a {
+                        |  class C {
+                        |    def hihi = List(1,2).map(_ * 2)
+                        |  }
+                        |}
+                        |package object a {
+                        |  def f = 1
+                        |}
+                        |""".stripMargin.trim
+
+  override def show(): Unit = {
+    val baos = new java.io.ByteArrayOutputStream()
+    Console.withOut(baos)(Console.withErr(baos)(compile()))
+    assert(!storeReporter.hasErrors, message = filteredInfos map (_.msg) mkString "; ")
+    val out = baos.toString("UTF-8")
+    // was 2 before the fix, the two PackageDefs for a would both contain the ClassDef for the closure
+    assert(out.lines.count(_ contains "class hihi$1") == 1, out)
+  }
+}