diff --git a/compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala b/compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala
index 259ac00b8cce..0c2654d3c42d 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala
+++ b/compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala
@@ -801,6 +801,7 @@ class TreeUnpickler(reader: TastyReader,
           ValDef(tpt)
         case TYPEDEF | TYPEPARAM =>
           if (sym.isClass) {
+            sym.owner.ensureCompleted() // scalacLinkedClass uses unforcedDecls. Make sure it does not miss anything.
             val companion = sym.scalacLinkedClass
 
             // Is the companion defined in the same Tasty file as `sym`?
diff --git a/tests/pos/i6989/Container_1.scala b/tests/pos/i6989/Container_1.scala
new file mode 100644
index 000000000000..3495bfd50169
--- /dev/null
+++ b/tests/pos/i6989/Container_1.scala
@@ -0,0 +1,12 @@
+package mypkg
+
+object Container {
+  class StringExtras(val s: String) extends AnyVal {
+    def op(item: Int): Int = ???
+  }
+}
+
+trait Container {
+  import Container._
+  implicit def mkStringExtras(s: String): StringExtras = new StringExtras(s)
+}
\ No newline at end of file
diff --git a/tests/pos/i6989/SimpleTest_2.scala b/tests/pos/i6989/SimpleTest_2.scala
new file mode 100644
index 000000000000..4b73d5aeba46
--- /dev/null
+++ b/tests/pos/i6989/SimpleTest_2.scala
@@ -0,0 +1,5 @@
+package mypkg
+
+class SimpleTest extends Container {
+  "foo".op(5)
+}