diff --git a/library/src/scala/tasty/util/ShowSourceCode.scala b/library/src/scala/tasty/util/ShowSourceCode.scala
index 2a47b063e9f0..84a60048a965 100644
--- a/library/src/scala/tasty/util/ShowSourceCode.scala
+++ b/library/src/scala/tasty/util/ShowSourceCode.scala
@@ -1142,7 +1142,9 @@ class ShowSourceCode[T <: Tasty with Singleton](tasty0: T) extends Show[T](tasty
       case '"' => "\\\""
       case '\'' => "\\\'"
       case '\\' => "\\\\"
-      case _ => if (ch.isControl) "\\0" + Integer.toOctalString(ch) else String.valueOf(ch)
+      case _ =>
+        // TODO(abeln): remove `asInstanceOf` once we do the more general bootstrapping of the compiler.
+        if (ch.isControl) "\\0" + Integer.toOctalString(ch) else String.valueOf(ch).asInstanceOf[String]
     }
 
     private def escapedString(str: String): String = str flatMap escapedChar