diff --git a/compiler/src/dotty/tools/dotc/semanticdb/DiagnosticOps.scala b/compiler/src/dotty/tools/dotc/semanticdb/DiagnosticOps.scala
index 975ea4ec8537..4bc6e1ecb026 100644
--- a/compiler/src/dotty/tools/dotc/semanticdb/DiagnosticOps.scala
+++ b/compiler/src/dotty/tools/dotc/semanticdb/DiagnosticOps.scala
@@ -4,9 +4,10 @@ import dotty.tools.dotc.reporting.Diagnostic
 import dotty.tools.dotc.{semanticdb => s}
 import dotty.tools.dotc.interfaces.Diagnostic.{ERROR, INFO, WARNING}
 import dotty.tools.dotc.core.Contexts.Context
+import scala.annotation.internal.sharable
 
 object DiagnosticOps:
-  private val asciiColorCodes = "\u001B\\[[;\\d]*m".r
+  @sharable private val asciiColorCodes = "\u001B\\[[;\\d]*m".r
   extension (d: Diagnostic)
     def toSemanticDiagnostic: s.Diagnostic =
       val severity = d.level match