diff --git a/java/debugger/impl/src/com/intellij/debugger/jdi/GeneratedReferenceType.java b/java/debugger/impl/src/com/intellij/debugger/jdi/GeneratedReferenceType.java
index e6cd19647e61..1206e3f675f2 100644
--- a/java/debugger/impl/src/com/intellij/debugger/jdi/GeneratedReferenceType.java
+++ b/java/debugger/impl/src/com/intellij/debugger/jdi/GeneratedReferenceType.java
@@ -246,7 +246,7 @@ public class GeneratedReferenceType implements ReferenceType {
 
   @Override
   public int compareTo(@NotNull ReferenceType o) {
-    return 0;
+    throw new IllegalStateException("not implemented");
   }
 
   @Override