diff --git a/compiler/src/dotty/tools/dotc/core/Symbols.scala b/compiler/src/dotty/tools/dotc/core/Symbols.scala
index 2e3661a52039..fb2b45268927 100644
--- a/compiler/src/dotty/tools/dotc/core/Symbols.scala
+++ b/compiler/src/dotty/tools/dotc/core/Symbols.scala
@@ -604,7 +604,7 @@ object Symbols {
 
     /** If this is either:
       *   - a top-level class and `-Yretain-trees` is set
-     *    - a top-level class loaded from TASTY and `-Xlink-optimise` is set
+     *    - a top-level class loaded from TASTY and `-tasty` or `-Xlink` is set
       * then return the TypeDef tree (possibly wrapped inside PackageDefs) for this class, otherwise EmptyTree.
       * This will force the info of the class.
       */
@@ -615,7 +615,8 @@ object Symbols {
         assert(myTree.isEmpty)
         val body = unpickler.body(ctx.addMode(Mode.ReadPositions))
         myTree = body.headOption.getOrElse(tpd.EmptyTree)
-        unpickler = null
+        if (!ctx.settings.tasty.value)
+          unpickler = null
       }
       myTree
     }
diff --git a/compiler/src/dotty/tools/dotc/core/tasty/TastyUnpickler.scala b/compiler/src/dotty/tools/dotc/core/tasty/TastyUnpickler.scala
index c062e3fbae8e..394399d6bf60 100644
--- a/compiler/src/dotty/tools/dotc/core/tasty/TastyUnpickler.scala
+++ b/compiler/src/dotty/tools/dotc/core/tasty/TastyUnpickler.scala
@@ -99,4 +99,6 @@ class TastyUnpickler(reader: TastyReader) {
   def unpickle[R](sec: SectionUnpickler[R]): Option[R] =
     for (reader <- sectionReader.get(sec.name)) yield
       sec.unpickle(reader, nameAtRef)
+
+  private[dotc] def bytes: Array[Byte] = reader.bytes
 }
diff --git a/compiler/src/dotty/tools/dotc/fromtasty/ReadTastyTreesFromClasses.scala b/compiler/src/dotty/tools/dotc/fromtasty/ReadTastyTreesFromClasses.scala
index 9ba0a19ca311..b7345f49e1c0 100644
--- a/compiler/src/dotty/tools/dotc/fromtasty/ReadTastyTreesFromClasses.scala
+++ b/compiler/src/dotty/tools/dotc/fromtasty/ReadTastyTreesFromClasses.scala
@@ -25,8 +25,13 @@ class ReadTastyTreesFromClasses extends FrontEnd {
         tree(className).flatMap {
           case (clsd, unpickled) =>
             if (unpickled.isEmpty) None
-            else Some(CompilationUnit.mkCompilationUnit(clsd, unpickled, forceTrees = true))
-
+            else {
+              val unit = CompilationUnit.mkCompilationUnit(clsd, unpickled, forceTrees = true)
+              val cls = clsd.symbol.asClass
+              unit.pickled += (cls -> cls.unpickler.unpickler.bytes)
+              cls.unpickler = null
+              Some(unit)
+            }
         }
       }
       // The TASTY section in a/b/C.class may either contain a class a.b.C, an object a.b.C, or both.
@@ -41,12 +46,13 @@ class ReadTastyTreesFromClasses extends FrontEnd {
     val clsd = ctx.base.staticRef(className)
     ctx.base.staticRef(className) match {
       case clsd: ClassDenotation =>
+        val cls = clsd.symbol.asClass
         def cannotUnpickle(reason: String) =
           ctx.error(s"class $className cannot be unpickled because $reason")
         def tryToLoad = clsd.infoOrCompleter match {
           case info: ClassfileLoader =>
             info.load(clsd)
-            Option(clsd.symbol.asClass.tree).orElse {
+            Option(cls.tree).orElse {
               cannotUnpickle(s"its class file ${info.classfile} does not have a TASTY attribute")
               None
             }
@@ -55,7 +61,7 @@ class ReadTastyTreesFromClasses extends FrontEnd {
             cannotUnpickle(s"its info of type ${info.getClass} is not a ClassfileLoader")
             None
         }
-        Option(clsd.symbol.asClass.tree).orElse(tryToLoad).map(tree => (clsd, tree))
+        Option(cls.tree).orElse(tryToLoad).map(tree => (clsd, tree))
 
       case _ =>
         ctx.error(s"class not found: $className")