diff --git a/compiler/src/dotty/tools/dotc/parsing/Scanners.scala b/compiler/src/dotty/tools/dotc/parsing/Scanners.scala
index 18f4f542b86c..f508ef38b6a0 100644
--- a/compiler/src/dotty/tools/dotc/parsing/Scanners.scala
+++ b/compiler/src/dotty/tools/dotc/parsing/Scanners.scala
@@ -1253,7 +1253,7 @@ object Scanners {
               nextChar()
             }
           }
-          val alt = if oct == LF then raw"\n" else f"\\u$oct%04x"
+          val alt = if oct == LF then raw"\n" else "\\" + f"u$oct%04x"
           error(s"octal escape literals are unsupported: use $alt instead", start)
           putChar(oct.toChar)
         }