diff --git a/platform/lang-impl/src/com/intellij/refactoring/BaseRefactoringProcessor.java b/platform/lang-impl/src/com/intellij/refactoring/BaseRefactoringProcessor.java
index 865026cd9a01..a22c14f226cd 100644
--- a/platform/lang-impl/src/com/intellij/refactoring/BaseRefactoringProcessor.java
+++ b/platform/lang-impl/src/com/intellij/refactoring/BaseRefactoringProcessor.java
@@ -216,6 +216,9 @@ public abstract class BaseRefactoringProcessor implements Runnable {
       }
     }
     if (isPreview) {
+      for (UsageInfo usage : usages) {
+        LOG.assertTrue(usage != null, getClass());
+      }
       previewRefactoring(usages);
     }
     else {