diff --git a/idea/src/org/jetbrains/jet/plugin/refactoring/changeSignature/JetChangeSignatureUsageProcessor.java b/idea/src/org/jetbrains/jet/plugin/refactoring/changeSignature/JetChangeSignatureUsageProcessor.java
index 77b83d1665b..4127364e860 100644
--- a/idea/src/org/jetbrains/jet/plugin/refactoring/changeSignature/JetChangeSignatureUsageProcessor.java
+++ b/idea/src/org/jetbrains/jet/plugin/refactoring/changeSignature/JetChangeSignatureUsageProcessor.java
@@ -126,6 +126,11 @@ public class JetChangeSignatureUsageProcessor implements ChangeSignatureUsagePro
     @Override
     public MultiMap<PsiElement, String> findConflicts(ChangeInfo info, Ref<UsageInfo[]> refUsages) {
         MultiMap<PsiElement, String> result = new MultiMap<PsiElement, String>();
+
+        if (!(info instanceof JetChangeInfo)) {
+            return result;
+        }
+
         Set<String> parameterNames = new HashSet<String>();
         JetChangeInfo changeInfo = (JetChangeInfo) info;
         PsiElement function = info.getMethod();