diff --git a/idea/src/org/jetbrains/kotlin/idea/inspections/migration/AbstractDiagnosticBasedMigrationInspection.kt b/idea/src/org/jetbrains/kotlin/idea/inspections/migration/AbstractDiagnosticBasedMigrationInspection.kt
index ec03886cb02..0f74a2df13b 100644
--- a/idea/src/org/jetbrains/kotlin/idea/inspections/migration/AbstractDiagnosticBasedMigrationInspection.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/inspections/migration/AbstractDiagnosticBasedMigrationInspection.kt
@@ -35,7 +35,7 @@ abstract class AbstractDiagnosticBasedMigrationInspection<T : KtElement>(
         }
 
         val actionsFactory = QuickFixes.getInstance().getActionFactories(diagnosticFactory).singleOrNull() ?: error("Must have one factory")
-        val problemDescriptors = arrayListOf<ProblemDescriptor>()
+        val problemDescriptors = mutableListOf<ProblemDescriptor>()
 
         file.accept(
             object : KtTreeVisitorVoid() {