diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 56b0b7457f83..b46f3ebede7b 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -126,7 +126,7 @@ jobs:
   community_build:
     runs-on: [self-hosted, Linux]
     container: lampepfl/dotty:2020-04-24
-
+    if: false
     steps:
       - name: Checkout cleanup script
         uses: actions/checkout@v2
@@ -167,11 +167,6 @@ jobs:
   test_sbt:
     runs-on: [self-hosted, Linux]
     container: lampepfl/dotty:2020-04-24
-    if: (
-          github.event_name == 'push' &&
-          startsWith(github.event.ref, 'refs/tags/')
-        ) ||
-        github.event_name == 'schedule'
 
     steps:
       - name: Checkout cleanup script
diff --git a/compiler/src/dotty/tools/dotc/core/SymDenotations.scala b/compiler/src/dotty/tools/dotc/core/SymDenotations.scala
index 44e9d162d8a6..2ddf92eb2eb6 100644
--- a/compiler/src/dotty/tools/dotc/core/SymDenotations.scala
+++ b/compiler/src/dotty/tools/dotc/core/SymDenotations.scala
@@ -1176,7 +1176,7 @@ object SymDenotations {
 
     final def scalacLinkedClass(using Context): Symbol =
       if (this.is(ModuleClass)) companionNamed(effectiveName.toTypeName)
-      else if (this.isClass) companionNamed(effectiveName.moduleClassName)
+      else if (this.isClass) companionNamed(effectiveName.moduleClassName).sourceModule.moduleClass
       else NoSymbol
 
     /** Find companion class symbol with given name, or NoSymbol if none exists.
diff --git a/sbt-dotty/sbt-test/scala2-compat/finagle/build.sbt b/sbt-dotty/sbt-test/scala2-compat/finagle/build.sbt
new file mode 100644
index 000000000000..a3c28b3d6943
--- /dev/null
+++ b/sbt-dotty/sbt-test/scala2-compat/finagle/build.sbt
@@ -0,0 +1,4 @@
+scalaVersion := sys.props("plugin.scalaVersion")
+
+libraryDependencies +=
+  ("com.twitter" %% "finagle-core" % "20.9.0").withDottyCompat(scalaVersion.value)
diff --git a/sbt-dotty/sbt-test/scala2-compat/finagle/i9916.scala b/sbt-dotty/sbt-test/scala2-compat/finagle/i9916.scala
new file mode 100644
index 000000000000..7c692f529428
--- /dev/null
+++ b/sbt-dotty/sbt-test/scala2-compat/finagle/i9916.scala
@@ -0,0 +1,10 @@
+import com.twitter.finagle.Stack
+import com.twitter.finagle.liveness.FailureAccrualFactory
+
+trait T {
+  def p: FailureAccrualFactory.Param
+}
+
+class A {
+  val t = Stack.Param[FailureAccrualFactory.Param](FailureAccrualFactory.Param(???))
+}
diff --git a/sbt-dotty/sbt-test/scala2-compat/finagle/project/plugins.sbt b/sbt-dotty/sbt-test/scala2-compat/finagle/project/plugins.sbt
new file mode 100644
index 000000000000..c17caab2d98c
--- /dev/null
+++ b/sbt-dotty/sbt-test/scala2-compat/finagle/project/plugins.sbt
@@ -0,0 +1 @@
+addSbtPlugin("ch.epfl.lamp" % "sbt-dotty" % sys.props("plugin.version"))
diff --git a/sbt-dotty/sbt-test/scala2-compat/finagle/test b/sbt-dotty/sbt-test/scala2-compat/finagle/test
new file mode 100644
index 000000000000..5df2af1f3956
--- /dev/null
+++ b/sbt-dotty/sbt-test/scala2-compat/finagle/test
@@ -0,0 +1 @@
+> compile
diff --git a/sbt-dotty/sbt-test/scala2-compat/i9916a/build.sbt b/sbt-dotty/sbt-test/scala2-compat/i9916a/build.sbt
new file mode 100644
index 000000000000..e9c732d4853a
--- /dev/null
+++ b/sbt-dotty/sbt-test/scala2-compat/i9916a/build.sbt
@@ -0,0 +1,15 @@
+val scala3Version = sys.props("plugin.scalaVersion")
+val scala2Version = "2.13.3"
+
+lazy val `i9916a-lib` = (project in file ("lib"))
+  .settings(scalaVersion := scala2Version)
+
+lazy val `i9916a-test` = (project in file ("main"))
+  .dependsOn(`i9916a-lib`)
+  .settings(
+    scalaVersion := scala3Version,
+    // https://github.com/sbt/sbt/issues/5369
+    projectDependencies := {
+      projectDependencies.value.map(_.withDottyCompat(scalaVersion.value))
+    }
+  )
diff --git a/sbt-dotty/sbt-test/scala2-compat/i9916a/lib/i9916a-lib.scala b/sbt-dotty/sbt-test/scala2-compat/i9916a/lib/i9916a-lib.scala
new file mode 100644
index 000000000000..44882333a2f5
--- /dev/null
+++ b/sbt-dotty/sbt-test/scala2-compat/i9916a/lib/i9916a-lib.scala
@@ -0,0 +1,7 @@
+package i9916a
+
+object Lib {
+  trait P
+  object P
+  def P(x: Int): P = ???
+}
diff --git a/sbt-dotty/sbt-test/scala2-compat/i9916a/main/i9916a-test.scala b/sbt-dotty/sbt-test/scala2-compat/i9916a/main/i9916a-test.scala
new file mode 100644
index 000000000000..1b10c3504ca7
--- /dev/null
+++ b/sbt-dotty/sbt-test/scala2-compat/i9916a/main/i9916a-test.scala
@@ -0,0 +1,5 @@
+import i9916a.Lib
+
+trait Test {
+  def foo: Lib.P
+}
diff --git a/sbt-dotty/sbt-test/scala2-compat/i9916a/project/plugins.sbt b/sbt-dotty/sbt-test/scala2-compat/i9916a/project/plugins.sbt
new file mode 100644
index 000000000000..c17caab2d98c
--- /dev/null
+++ b/sbt-dotty/sbt-test/scala2-compat/i9916a/project/plugins.sbt
@@ -0,0 +1 @@
+addSbtPlugin("ch.epfl.lamp" % "sbt-dotty" % sys.props("plugin.version"))
diff --git a/sbt-dotty/sbt-test/scala2-compat/i9916a/test b/sbt-dotty/sbt-test/scala2-compat/i9916a/test
new file mode 100644
index 000000000000..2a848354ed12
--- /dev/null
+++ b/sbt-dotty/sbt-test/scala2-compat/i9916a/test
@@ -0,0 +1 @@
+> i9916a-test/compile
diff --git a/sbt-dotty/sbt-test/scala2-compat/i9916b/build.sbt b/sbt-dotty/sbt-test/scala2-compat/i9916b/build.sbt
new file mode 100644
index 000000000000..51a2d056ddad
--- /dev/null
+++ b/sbt-dotty/sbt-test/scala2-compat/i9916b/build.sbt
@@ -0,0 +1,15 @@
+val scala3Version = sys.props("plugin.scalaVersion")
+val scala2Version = "2.13.3"
+
+lazy val `i9916b-lib` = (project in file ("lib"))
+  .settings(scalaVersion := scala2Version)
+
+lazy val `i9916b-test` = (project in file ("main"))
+  .dependsOn(`i9916b-lib`)
+  .settings(
+    scalaVersion := scala3Version,
+    // https://github.com/sbt/sbt/issues/5369
+    projectDependencies := {
+      projectDependencies.value.map(_.withDottyCompat(scalaVersion.value))
+    }
+  )
diff --git a/sbt-dotty/sbt-test/scala2-compat/i9916b/lib/i9916b-lib.scala b/sbt-dotty/sbt-test/scala2-compat/i9916b/lib/i9916b-lib.scala
new file mode 100644
index 000000000000..0ce017246f86
--- /dev/null
+++ b/sbt-dotty/sbt-test/scala2-compat/i9916b/lib/i9916b-lib.scala
@@ -0,0 +1,7 @@
+package i9916b
+
+trait T {
+  class A
+  object A
+  def A(x: Int): Unit = ???
+}
diff --git a/sbt-dotty/sbt-test/scala2-compat/i9916b/main/i9916b-test.scala b/sbt-dotty/sbt-test/scala2-compat/i9916b/main/i9916b-test.scala
new file mode 100644
index 000000000000..fb702d1a8617
--- /dev/null
+++ b/sbt-dotty/sbt-test/scala2-compat/i9916b/main/i9916b-test.scala
@@ -0,0 +1,5 @@
+import i9916b.T
+
+trait Test {
+  def foo: T
+}
diff --git a/sbt-dotty/sbt-test/scala2-compat/i9916b/project/plugins.sbt b/sbt-dotty/sbt-test/scala2-compat/i9916b/project/plugins.sbt
new file mode 100644
index 000000000000..c17caab2d98c
--- /dev/null
+++ b/sbt-dotty/sbt-test/scala2-compat/i9916b/project/plugins.sbt
@@ -0,0 +1 @@
+addSbtPlugin("ch.epfl.lamp" % "sbt-dotty" % sys.props("plugin.version"))
diff --git a/sbt-dotty/sbt-test/scala2-compat/i9916b/test b/sbt-dotty/sbt-test/scala2-compat/i9916b/test
new file mode 100644
index 000000000000..064736132510
--- /dev/null
+++ b/sbt-dotty/sbt-test/scala2-compat/i9916b/test
@@ -0,0 +1 @@
+> i9916b-test/compile