diff --git a/compiler/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala b/compiler/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala
index f876c87e8920..806f39ee0425 100644
--- a/compiler/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala
+++ b/compiler/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala
@@ -151,7 +151,6 @@ class Scala2Unpickler(bytes: Array[Byte], classRoot: ClassDenotation, moduleClas
   assert(moduleRoot.isTerm)
 
   checkVersion(using ictx)
-  checkScala2Stdlib(using ictx)
 
   private val loadingMirror = defn(using ictx) // was: mirrorThatLoaded(classRoot)
 
@@ -238,9 +237,6 @@ class Scala2Unpickler(bytes: Array[Byte], classRoot: ClassDenotation, moduleClas
         " in " + source)
   }
 
-  private def checkScala2Stdlib(using Context): Unit =
-    assert(!ctx.settings.YcompileScala2Library.value, "No Scala 2 libraries should be unpickled under -Ycompile-scala2-library")
-
   /** The `decls` scope associated with given symbol */
   protected def symScope(sym: Symbol): Scope = symScopes.getOrElseUpdate(sym, newScope(0))
 
diff --git a/project/Build.scala b/project/Build.scala
index 0e3f725bb180..9f1711540269 100644
--- a/project/Build.scala
+++ b/project/Build.scala
@@ -1063,6 +1063,7 @@ object Build {
       },
       Compile / doc / scalacOptions += "-Ydocument-synthetic-types",
       scalacOptions += "-Ycompile-scala2-library",
+      scalacOptions += "-Yscala2Unpickler:never",
       scalacOptions -= "-Xfatal-warnings",
       Compile / compile / logLevel := Level.Error,
       ivyConfigurations += SourceDeps.hide,