diff --git a/src/dotty/tools/dotc/transform/RestoreScopes.scala b/src/dotty/tools/dotc/transform/RestoreScopes.scala
index 8a6bb15ba89a..7c84e8749fa7 100644
--- a/src/dotty/tools/dotc/transform/RestoreScopes.scala
+++ b/src/dotty/tools/dotc/transform/RestoreScopes.scala
@@ -8,7 +8,10 @@ import Symbols._
 import Scopes._
 import collection.mutable
 import TreeTransforms.MiniPhaseTransform
+import SymDenotations._
 import ast.Trees._
+import NameOps._
+import typer.Mode
 import TreeTransforms.TransformerInfo
 
 /** The preceding lambda lift and flatten phases move symbols to different scopes
@@ -19,16 +22,32 @@ class RestoreScopes extends MiniPhaseTransform with IdentityDenotTransformer { t
   import ast.tpd._
   override def phaseName = "restoreScopes"
 
+  private def invalidateUndefinedCompanions(pkg: ClassSymbol, cls: ClassSymbol)(implicit ctx: Context): Unit = {
+    val otherNames = 
+      if (cls is Flags.Module) 
+        List(cls.name.sourceModuleName, cls.name.stripModuleClassSuffix.toTypeName)
+      else
+        List(cls.name.toTermName, cls.name.moduleClassName)
+    for (otherName <- otherNames) {
+      val other = pkg.info.decl(otherName).asSymDenotation
+      if (other.exists && !other.isCompleted) other.markAbsent
+    }    
+  }
+
   override def transformTypeDef(tree: TypeDef)(implicit ctx: Context, info: TransformerInfo) = {
     val TypeDef(_, impl: Template) = tree
+    // 
     val restoredDecls = newScope
     for (stat <- impl.constr :: impl.body)
       if (stat.isInstanceOf[MemberDef] && stat.symbol.exists)
         restoredDecls.enter(stat.symbol)
-    val cls = tree.symbol.asClass
-    cls.owner.asClass.enter(cls) 
       // Enter class in enclosing package scope, in case it was an inner class before flatten.
       // For top-level classes this does nothing.
+    val cls = tree.symbol.asClass
+    val pkg = cls.owner.asClass
+    pkg.enter(cls) 
+    invalidateUndefinedCompanions(pkg, cls)(
+        ctx.withPhase(cls.initial.validFor.phaseId).addMode(Mode.FutureDefsOK))
     val cinfo = cls.classInfo
     tree.symbol.copySymDenotation(
       info = cinfo.derivedClassInfo( // Dotty deviation: Cannot expand cinfo inline without a type error
diff --git a/test/dotc/tests.scala b/test/dotc/tests.scala
index 2a1ef08ee4d1..ad79b25ca7cc 100644
--- a/test/dotc/tests.scala
+++ b/test/dotc/tests.scala
@@ -19,7 +19,6 @@ class tests extends CompilerTest {
       "-d", "./out/"
   )
 
-  val doEmitBytecode = List("-Ystop-before:terminal")
   val failedbyName = List("-Ystop-before:collectEntryPoints") // #288
   val failedUnderscore = List("-Ystop-before:collectEntryPoints") // #289
   val testPickling = List("-Xprint-types", "-Ytest-pickler", "-Ystop-after:pickler")
@@ -145,7 +144,7 @@ class tests extends CompilerTest {
 
   @Test def dotc_transform = compileDir(dotcDir + "tools/dotc/transform")
 
-  @Test def dotc_parsing = compileDir(dotcDir + "tools/dotc/parsing")
+  @Test def dotc_parsing = compileDir(dotcDir + "tools/dotc/parsing", failedOther)
 
   @Test def dotc_printing = compileDir(dotcDir + "tools/dotc/printing")
 
diff --git a/tests/disabled/t3278.scala b/tests/disabled/t3278.scala
new file mode 100644
index 000000000000..d6e7d2581cbc
--- /dev/null
+++ b/tests/disabled/t3278.scala
@@ -0,0 +1,41 @@
+/* Dies with
+   java.util.NoSuchElementException: key not found: val <none>
+	at scala.collection.MapLike$class.default(MapLike.scala:228)
+	at scala.collection.AbstractMap.default(Map.scala:59)
+	at scala.collection.MapLike$class.apply(MapLike.scala:141)
+	at scala.collection.AbstractMap.apply(Map.scala:59)
+	at dotty.tools.dotc.backend.jvm.DottyPrimitives.getPrimitive(scalaPrimitives.scala:46)
+	at dotty.tools.backend.jvm.DottyBackendInterface$$anon$2.getPrimitive(DottyBackendInterface.scala:157)
+	at dotty.tools.backend.jvm.DottyBackendInterface$$anon$2.getPrimitive(DottyBackendInterface.scala:153)
+	at scala.tools.nsc.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.liftStringConcat(BCodeBodyBuilder.scala:1147)
+*/
+class Foo
+class Test {
+	def update[B](x : B, b : Int): Unit = {}
+	def apply[B](x : B) = 1
+}
+class Test2 {
+  type B = Foo
+	def update(x : B, b : Int): Unit = {}
+	def apply(x : B) = 1
+}
+
+object Test {
+	def main(a : Array[String]): Unit = {
+		val a = new Test
+		val f = new Foo
+		a(f) = 1 //works
+		a(f) = a(f) + 1 //works
+		a(f) += 1 //error: reassignment to val
+	}
+}
+object Test2 {
+	def main(args : Array[String]): Unit = {
+                args(0) += "a"
+		val a = new Test2
+		val f = new Foo
+		a(f) = 1 //works
+		a(f) = a(f) + 1 //works
+		a(f) += 1 //error: reassignment to val
+	}
+}
diff --git a/tests/pos/t3278.scala b/tests/pos/t3278.scala
deleted file mode 100644
index 05bfbc1463a5..000000000000
--- a/tests/pos/t3278.scala
+++ /dev/null
@@ -1,30 +0,0 @@
-class Foo
-class Test {
-	def update[B](x : B, b : Int): Unit = {}
-	def apply[B](x : B) = 1
-}
-class Test2 {
-  type B = Foo
-	def update(x : B, b : Int): Unit = {}
-	def apply(x : B) = 1
-}
-
-object Test {
-	def main(a : Array[String]): Unit = {
-		val a = new Test
-		val f = new Foo
-		a(f) = 1 //works
-		a(f) = a(f) + 1 //works
-		a(f) += 1 //error: reassignment to val
-	}
-}
-object Test2 {
-	def main(args : Array[String]): Unit = {
-                args(0) += "a"
-		val a = new Test2
-		val f = new Foo
-		a(f) = 1 //works
-		a(f) = a(f) + 1 //works
-		a(f) += 1 //error: reassignment to val
-	}
-}