diff --git a/compiler/src/dotty/tools/dotc/ast/Desugar.scala b/compiler/src/dotty/tools/dotc/ast/Desugar.scala
index df3809b64281..dd15a25031d5 100644
--- a/compiler/src/dotty/tools/dotc/ast/Desugar.scala
+++ b/compiler/src/dotty/tools/dotc/ast/Desugar.scala
@@ -341,8 +341,9 @@ object desugar {
       case _ => false
     }
 
-    val isCaseClass  = mods.is(Case) && !mods.is(Module)
-    val isCaseObject = mods.is(Case) && mods.is(Module)
+    val isObject = mods.is(Module)
+    val isCaseClass  = mods.is(Case) && !isObject
+    val isCaseObject = mods.is(Case) && isObject
     val isImplicit = mods.is(Implicit)
     val isInstance = isImplicit && mods.mods.exists(_.isInstanceOf[Mod.Instance])
     val isEnum = mods.isEnumClass && !mods.is(Module)
@@ -527,13 +528,13 @@ object desugar {
       else Nil
     }
 
-    // Case classes and case objects get Product parents
-    // Enum cases get an inferred parent if no parents are given
     var parents1 = parents
     if (isEnumCase && parents.isEmpty)
       parents1 = enumClassTypeRef :: Nil
     if (isCaseClass | isCaseObject)
       parents1 = parents1 :+ scalaDot(str.Product.toTypeName) :+ scalaDot(nme.Serializable.toTypeName)
+    else if (isObject)
+      parents1 = parents1 :+ scalaDot(nme.Serializable.toTypeName)
     if (isEnum)
       parents1 = parents1 :+ ref(defn.EnumType)
 
diff --git a/compiler/src/dotty/tools/dotc/ast/Trees.scala b/compiler/src/dotty/tools/dotc/ast/Trees.scala
index 6cc697bfb5d6..1d20f20e5d89 100644
--- a/compiler/src/dotty/tools/dotc/ast/Trees.scala
+++ b/compiler/src/dotty/tools/dotc/ast/Trees.scala
@@ -887,7 +887,8 @@ object Trees {
 
   // ----- Generic Tree Instances, inherited from `tpt` and `untpd`.
 
-  abstract class Instance[T >: Untyped <: Type] { inst =>
+  // FIXME: Work around cyclic reference by writing `Types.Type` instead of `Type`
+  abstract class Instance[T >: Untyped <: Types.Type] { inst =>
 
     type Tree = Trees.Tree[T]
     type TypTree = Trees.TypTree[T]
diff --git a/sbt-bridge/test/xsbt/ExtractUsedNamesSpecification.scala b/sbt-bridge/test/xsbt/ExtractUsedNamesSpecification.scala
index befe2dd433d3..9106d9f5304a 100644
--- a/sbt-bridge/test/xsbt/ExtractUsedNamesSpecification.scala
+++ b/sbt-bridge/test/xsbt/ExtractUsedNamesSpecification.scala
@@ -79,10 +79,10 @@ class ExtractUsedNamesSpecification {
     val usedNames = compilerForTesting.extractUsedNamesFromSrc(srcA, srcB, srcC, srcD)
     val scalaVersion = scala.util.Properties.versionNumberString
     val namesA = standardNames ++ Set("Nothing", "Any")
-    val namesAX = standardNames ++ Set("x", "T", "A", "Nothing", "Any")
+    val namesAX = standardNames ++ objectStandardNames ++ Set("x", "T", "A", "Nothing", "Any", "scala")
     val namesB = Set("A", "Int", "A;init;", "Unit")
-    val namesC = Set("B;init;", "B", "Unit")
-    val namesD = standardNames ++ Set("C", "X", "foo", "Int", "T")
+    val namesC = objectStandardNames ++ Set("B;init;", "B", "Unit")
+    val namesD = standardNames ++ objectStandardNames ++ Set("C", "X", "foo", "Int", "T")
     assertEquals(namesA, usedNames("A"))
     assertEquals(namesAX, usedNames("A.X"))
     assertEquals(namesB, usedNames("B"))
@@ -130,23 +130,30 @@ class ExtractUsedNamesSpecification {
                   |""".stripMargin
     val compilerForTesting = new ScalaCompilerForUnitTesting
     val usedNames = compilerForTesting.extractUsedNamesFromSrc(src1, src2)
-    val expectedNames_lista = standardNames ++ Set("B", "lista", "List", "A")
-    val expectedNames_at = standardNames ++ Set("B", "at", "A", "T", "X0", "X1")
-    val expectedNames_as = standardNames ++ Set("B", "as", "S", "Y")
-    val expectedNames_foo = standardNames ++ Set("B",
-                                                 "foo",
-                                                 "M",
-                                                 "N",
-                                                 "Predef",
-                                                 "???",
-                                                 "Nothing")
-    val expectedNames_bar = standardNames ++ Set("B",
-                                                 "bar",
-                                                 "P1",
-                                                 "P0",
-                                                 "Predef",
-                                                 "???",
-                                                 "Nothing")
+    val expectedNames_lista =
+      standardNames ++ objectStandardNames ++ Set("B", "lista", "List", "A")
+    val expectedNames_at =
+      standardNames ++ objectStandardNames ++  Set("B", "at", "A", "T", "X0", "X1")
+    val expectedNames_as =
+      standardNames ++ objectStandardNames ++  Set("B", "as", "S", "Y")
+    val expectedNames_foo =
+      standardNames ++ objectStandardNames ++
+       Set("B",
+           "foo",
+           "M",
+           "N",
+           "Predef",
+           "???",
+           "Nothing")
+    val expectedNames_bar =
+      standardNames ++ objectStandardNames ++
+       Set("B",
+           "bar",
+           "P1",
+           "P0",
+           "Predef",
+           "???",
+           "Nothing")
     assertEquals(expectedNames_lista, usedNames("Test_lista"))
     assertEquals(expectedNames_at, usedNames("Test_at"))
     assertEquals(expectedNames_as, usedNames("Test_as"))
@@ -167,7 +174,7 @@ class ExtractUsedNamesSpecification {
                     |""".stripMargin
     val compilerForTesting = new ScalaCompilerForUnitTesting
     val usedNames = compilerForTesting.extractUsedNamesFromSrc(srcFoo, srcBar)
-    val expectedNames = standardNames ++ Set("Outer", "TypeInner", "Inner", "Int")
+    val expectedNames = standardNames ++ objectStandardNames ++ Set("Outer", "TypeInner", "Inner", "Int")
     assertEquals(expectedNames, usedNames("Bar"))
   }
 
@@ -302,4 +309,9 @@ class ExtractUsedNamesSpecification {
     // the return type of the default constructor is Unit
     "Unit"
   )
+
+  private val objectStandardNames = Set(
+    // all Dotty objects extend scala.Serializable
+    "scala", "Serializable"
+  )
 }
diff --git a/scala-backend b/scala-backend
index 9ef70dd9b9ee..1447a7fbbc5d 160000
--- a/scala-backend
+++ b/scala-backend
@@ -1 +1 @@
-Subproject commit 9ef70dd9b9eeec11cfb72dabb57c61198fa18a20
+Subproject commit 1447a7fbbc5dd51a5e561c57bc873576e1ba542c