diff --git a/java/java-impl-refactorings/src/com/intellij/refactoring/changeSignature/JavaChangeSignatureUsageProcessor.java b/java/java-impl-refactorings/src/com/intellij/refactoring/changeSignature/JavaChangeSignatureUsageProcessor.java
index edba4ff3f6eb..b6b04f18d858 100644
--- a/java/java-impl-refactorings/src/com/intellij/refactoring/changeSignature/JavaChangeSignatureUsageProcessor.java
+++ b/java/java-impl-refactorings/src/com/intellij/refactoring/changeSignature/JavaChangeSignatureUsageProcessor.java
@@ -1112,11 +1112,13 @@ public class JavaChangeSignatureUsageProcessor implements ChangeSignatureUsagePr
                                                         final PsiParameterList list,
                                                         boolean[] toRemoveParm,
                                                         final PsiElement methodBody) throws IncorrectOperationException {
+    PsiUtilCore.ensureValid(list);
     List<FieldConflictsResolver> conflictResolvers = new ArrayList<>();
     for (PsiParameter parameter : newParms) {
       conflictResolvers.add(new FieldConflictsResolver(parameter.getName(), methodBody));
     }
     ChangeSignatureUtil.synchronizeList(list, Arrays.asList(newParms), ParameterList.INSTANCE, toRemoveParm);
+    LOG.assertTrue(list.getContainingFile() != null, "No containing file for: " + list.getClass());
     JavaCodeStyleManager.getInstance(list.getProject()).shortenClassReferences(list);
     for (FieldConflictsResolver fieldConflictsResolver : conflictResolvers) {
       fieldConflictsResolver.fix();